The largest association of meteorologists and climate scientists issued a fresh statement on the scientific evidence for human-driven climate change and possible impacts. This is an update from the 2007 statement that can be found here: http://www.ametsoc.org/policy/2007climatechange.html
More on climate change on Dot Earth:
http://j.mp/dotBasic http://j.mp/dotBasics
IB Extended Essay Sample APA 2018-2019 by WritingMetier.comWriting Metier
APA style International Baccalaureate Extended Essay Sample years 2018-2019 written by WritingMetier.com
Topic:
Adverse effects of global warming and what can be done to reduce it?
Climate Change Basics: Issues and Impacts for BoatingNASBLA
State Climatologist David Zierden presented Climate Change Basics: Issues and Impacts for Boating to the National Association of State Boating Law Administrators on September 9, 2008
The Earth’s climate is changing. Temperatures are rising, snow and rainfall patterns are shifting, and more extreme climate events—like heavy rainstorms and record-high temperatures, are already taking place. One important way to track and communicate the causes and effects of climate change is
through the use of indicators. An indicator represents the state or trend of certain environmental or societal conditions over a given area and a specified period of time. This lesson highlights all those indicators for a better understanding of climate change.
Few global trends have been as controversial as climate change and the Earth’s warming. The Earth has gone through many shifts in cooling and warming driven by natural factors like the sun’s energy or variations in its orbit, but the trend scientists have seen over the past 50 years is unmistakable.
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions, or in the distribution of weather around the average conditions (i.e., more or fewer extreme weather events). Climate change is caused by factors such as biotic processes, variations in solar radiation received by Earth, plate tectonics, and volcanic eruptions. Certain human activities have also been identified as significant causes of recent climate change, often referred to as "global warming"
Scientists actively work to understand past and future climate by using observations and theoretical models. A climate record — extending deep into the Earth's past — has been assembled, and continues to be built up, based on geological evidence from borehole temperature profiles, cores removed from deep accumulations of ice, floral and faunal records, glacial and periglacial processes, stable-isotope and other analyses of sediment layers, and records of past sea levels. More recent data are provided by the instrumental record. General circulation models, based on the physical sciences, are often used in theoretical approaches to match past climate data, make future projections, and link causes and effects in climate change.
IB Extended Essay Sample APA 2018-2019 by WritingMetier.comWriting Metier
APA style International Baccalaureate Extended Essay Sample years 2018-2019 written by WritingMetier.com
Topic:
Adverse effects of global warming and what can be done to reduce it?
Climate Change Basics: Issues and Impacts for BoatingNASBLA
State Climatologist David Zierden presented Climate Change Basics: Issues and Impacts for Boating to the National Association of State Boating Law Administrators on September 9, 2008
The Earth’s climate is changing. Temperatures are rising, snow and rainfall patterns are shifting, and more extreme climate events—like heavy rainstorms and record-high temperatures, are already taking place. One important way to track and communicate the causes and effects of climate change is
through the use of indicators. An indicator represents the state or trend of certain environmental or societal conditions over a given area and a specified period of time. This lesson highlights all those indicators for a better understanding of climate change.
Few global trends have been as controversial as climate change and the Earth’s warming. The Earth has gone through many shifts in cooling and warming driven by natural factors like the sun’s energy or variations in its orbit, but the trend scientists have seen over the past 50 years is unmistakable.
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions, or in the distribution of weather around the average conditions (i.e., more or fewer extreme weather events). Climate change is caused by factors such as biotic processes, variations in solar radiation received by Earth, plate tectonics, and volcanic eruptions. Certain human activities have also been identified as significant causes of recent climate change, often referred to as "global warming"
Scientists actively work to understand past and future climate by using observations and theoretical models. A climate record — extending deep into the Earth's past — has been assembled, and continues to be built up, based on geological evidence from borehole temperature profiles, cores removed from deep accumulations of ice, floral and faunal records, glacial and periglacial processes, stable-isotope and other analyses of sediment layers, and records of past sea levels. More recent data are provided by the instrumental record. General circulation models, based on the physical sciences, are often used in theoretical approaches to match past climate data, make future projections, and link causes and effects in climate change.
Global warming is a long-term rise in the average temperature of the Earths climate system, an aspect of climate change shown by temperature measurements and by multiple effects of the warming. A worldwide temperature alteration, the wonder of expanding normal air temperatures close to the surface of Earth over the past one to two centuries. Atmosphere researchers have since the mid-twentieth century assembled itemized perceptions of different climate marvels, for example, temperatures, precipitation, and storms and of related influences on atmosphere, for example, sea flows and the airs compound creation . These information demonstrate that Earths atmosphere has changed over pretty much every possible timescale since the start of geologic time and that the influence of human exercises since in any event the start of the Industrial Revolution has been profoundly woven into the specific texture of environmental change. Prof. S. S. Patil "A Study on Global Warming and its Effects" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-2 , February 2019, URL: https://www.ijtsrd.com/papers/ijtsrd20301.pdf
Paper URL: https://www.ijtsrd.com/humanities-and-the-arts/geography/20301/a-study-on-global-warming-and-its-effects/prof-s-s-patil
Climate Change Effects on Dengue Fever and Chagas' DiseaseAbigail Lukowicz
Undergraduate capstone project for the class Ecology of Infectious Diseases. This research highlights potential effects of climate change on the Dengue Fever vector (Aedes aegypti) and the Chagas' disease vector (Triatomine spp.). Collaboration with Michael Andreone and Daniel Pastika.
Vivid description about climate change
A NASA database based presentation.
Geoengineering, solar , Mitigation and Adaption
a social cause , vital signs of planet
brief intoduction
www.climate.nasa.gov
Global warming is a long-term rise in the average temperature of the Earths climate system, an aspect of climate change shown by temperature measurements and by multiple effects of the warming. A worldwide temperature alteration, the wonder of expanding normal air temperatures close to the surface of Earth over the past one to two centuries. Atmosphere researchers have since the mid-twentieth century assembled itemized perceptions of different climate marvels, for example, temperatures, precipitation, and storms and of related influences on atmosphere, for example, sea flows and the airs compound creation . These information demonstrate that Earths atmosphere has changed over pretty much every possible timescale since the start of geologic time and that the influence of human exercises since in any event the start of the Industrial Revolution has been profoundly woven into the specific texture of environmental change. Prof. S. S. Patil "A Study on Global Warming and its Effects" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-2 , February 2019, URL: https://www.ijtsrd.com/papers/ijtsrd20301.pdf
Paper URL: https://www.ijtsrd.com/humanities-and-the-arts/geography/20301/a-study-on-global-warming-and-its-effects/prof-s-s-patil
Climate Change Effects on Dengue Fever and Chagas' DiseaseAbigail Lukowicz
Undergraduate capstone project for the class Ecology of Infectious Diseases. This research highlights potential effects of climate change on the Dengue Fever vector (Aedes aegypti) and the Chagas' disease vector (Triatomine spp.). Collaboration with Michael Andreone and Daniel Pastika.
Vivid description about climate change
A NASA database based presentation.
Geoengineering, solar , Mitigation and Adaption
a social cause , vital signs of planet
brief intoduction
www.climate.nasa.gov
Potential Global Warming and Sea Level Rise; Impact of Climate Change on Ene...Jack Onyisi Abebe
This presentation discusses the Potential Global Warming and Sea Level Rise; Impact of Climate Change on Energy Use, Water and Water Quality and Availability
Over millions of years, species become adapted to survive in the conditions in which they live. A stable climate supports this process and allows living things to thrive. If the climate changes quickly, organisms don’t have enough time to adapt to new conditions and may no longer be able to survive.
a change in global or regional climate patterns, in particular a change apparent from the mid to late 20th century onwards and attributed largely to the increased levels of atmospheric carbon dioxide produced by the use of fossil fuels.
a change in global or regional climate patterns, in particular a change apparent from the mid to late 20th century onwards and attributed largely to the increased levels of atmospheric carbon dioxide produced by the use of fossil fuels.
Environmental conditions play a key role in defining the function an.pdfanandhomeneeds
Environmental conditions play a key role in defining the function and distribution of plants, in
combination with other factors. Changes in long term environmental conditions that can be
collectively coined climate change are known to have had enormous impacts on plant diversity
patterns in the future and are seen as having significant current impacts. It is predicted that
climate change will remain one of the major drivers of biodiversity patterns in the future.
The Earth has experienced a constantly changing climate in the time since plants first evolved. In
comparison to the present day, this history has seen Earth as cooler, warmer, drier and wetter,
and CO2 (carbon dioxide) concentrations have been both higher and lower. These changes have
been reflected by constantly shifting vegetation, for example forest communities dominating
most areas in interglacial periods, and herbaceous communities dominating during glacial
periods. It has been shown that past climatic change has been a major driver of the processes of
speciation and extinction. The best known example of this is the Carboniferous Rainforest
Collapse which occurred 350 million years ago. This event decimated amphibian populations
and spurred on the evolution of reptiles
Greenhouse effect - the mechanism
The sun radiates solar energy on earth. The larger part of this energy (45%) is radiated back into
space. Greenhouse gases in the atmosphere contribute to global warming by adsorption and
reflection of atmospheric and solar energy. This natural phenomenon is what we call the
greenhouse effect. It is agreed that the greenhouse effect is correlated with global temperature
change. The primary greenhouse gases in the Earth’s atmosphere are water vapor, carbon
dioxide, methane, nitrous oxide, and ozone
Mechanism of global warming:
i. The incoming radiation from the Sun is mostly in the form of visible light and nearby
wavelengths, largely in the range 0.2 – 4 1m, corresponding to the Sun’s radioactive temperature
of 6,000 K. Almost half the radiation is in the form of “visible” light, which our eyes are adapted
to use.
ii. About 50% of the Sun’s energy is absorbed at the earth’s surface and the rest is reflected or
absorbed by the atmosphere. The reflection of light back into space – largely by clouds – does
not much affect the basic mechanism; this light, effectively, is lost to the system.
iii (a) Earth absorbs most of the sunlight it receives; The absorbed energy warms the surface; (b)
Earth then emits the absorbed light’s energy as infrared light; (c) greenhouse gases absorb a lot
of the infrared light before it can leave our atmosphere; (d) being absorbed slows the rate at
which energy escapes to space; and (e) the slower passage of energy heats up the atmosphere,
water, and ground. By increasing the amount of greenhouse gases in the atmosphere, humans are
increasing the atmosphere’s absorption of infrared light, thereby warming Earth and disrupting
global climate patterns.
Effec.
Andrew Revkin's 1994 profile of the masterful luthier Linda Manzer. Blending spruce, sweat and sawdust, Linda Manzer builds guitars that
dazzle.
Photos by Peter Sibbald https://petersibbald.visura.co
Linda Manzer:
https://manzer.com
Andy Revkin:
http://j.mp/revkinlinks
In 1985, my editor, Scott DeGarmo, asked me to write a cover story on the future of the automobile - when the future was the Ford Taurus. It's now kind of a museum artifact and I hope you enjoy it and offer feedback.
This is the core of a webinar Andy Revkin conducted with folks at Columbia Climate School to explore how scientists, scholars and others seeking to craft a better human journey can make the most of Twitter even as Elon Musk's purchase disrupts things. We also talked about alternatives, none of which Revkin sees as remotely competing with the capacities Twitter offers for a long time. (It took a decade of relentless programming, regulatory and other work to build the Twitter we know.)
Subscribe to Revkin's Sustain What newsletter and webcasts to engage and drive the conversation further:
https://revkin.substack.com/subscribe #socialmedia #sustainability #climate
This is a fantastic case study and overview showing how businesses can prepare for the hazards around them to cut the scope of impacts - preventing a natural hazard from becoming an unnatural disaster.
It centers on the experience and work of Parsons Manufacturing, a company that suffered a direct hit from an EF-4 tornado in 2004 but avoided any deaths.
Learn more at the company website:
https://www.parsonscompany.com/about/
A #COP26 presentation by Zainab Usman of Carnegie Endowment for International Peace and Katie Auth of Energy for Development, building on this paper: September 28, 2021
REFRAMING CLIMATE JUSTICE FOR DEVELOPMENT: SIX PRINCIPLES FOR SUPPORTING INCLUSIVE AND EQUITABLE ENERGY TRANSITIONS IN LOW-EMITTING ENERGY-POOR AFRICAN COUNTRIES
By Mimi Alemayehou, Katie Auth, Murefu Barasa, Morgan Bazilian, Brad Handler, Uzo Iweala, Todd Moss, Rose Mutiso, Zainab Usman
Advancing inclusive and equitable energy transitions is one of this century’s most vital global challenges, and one in which development finance will play a crucial role. References to justice and equity are widespread in international climate policy, and are increasingly being used by development organizations to guide their own work, including support for energy transitions.
But prevailing definitions of climate justice rarely fully capture the priorities, challenges and perspectives of low-emitting energy-poor countries, the vast majority of which are in sub-Saharan Africa. When applied to development policy, this gap risks prioritizing near-term emissions reductions over broader support for economic development and energy transformation, with comparatively little climate benefit. This could severely hinder poverty alleviation, development, and climate resilience — the very opposite of justice. We need energy transitions that are truly ‘just and inclusive.’ What does this mean for development funders and financiers, and how should it drive their approach to supporting energy transitions in the lowest-income countries?
Rene Dubos was a masterful biologist, Pulitzer-winning essayist and humanist. Read the story behind this essay in Andy Revkin's homage to Dubos here: http://j.mp/despairingoptimist
This is a summary of the three-week international survey of the vaquita refuge in heavily fished waters of the northern Gulf of California of the coast of Mexico's Baja California state. It shows what can be accomplished with a fresh effort in the fall of 2021.
The expedition included scientists and conservationists from Mexico, the United States and Canada.
This chapter on climate change as news, by Andrew Revkin is from "Climate Change: What It Means for Us, Our Children, and Our Grandchildren" - edited by Joseph F. C. DiMento and Pamela Doughman
MIT Press 2007, updated edition, 2014
https://scholar.google.com/citations?view_op=view_citation&hl=en&user=xsxkAlEAAAAJ&citation_for_view=xsxkAlEAAAAJ:edDO8Oi4QzsC
Alice Bell's new book on the history of climate change knowledge and inaction is fantastic. Some have missed what is NOT in the CIA's 1974 assessment of climate change and security risk. There's no mention of global warming from carbon dioxide. Here's a Guardian excerpt from Alice's book: https://www.theguardian.com/science/2021/jul/05/sixty-years-of-climate-change-warnings-the-signs-that-were-missed-and-ignored
Here's the original CIA document without text recognition: https://www.hsdl.org/?abstract&did=725433
A deep early look at how supercomputer security became a prime concern of the Reagan administration - with climate science in the mix.
More context in Andrew Revkin's prize-winning March 1985 Science Digest article on nuclear winter:
https://www.slideshare.net/Revkin/hard-facts-about-nuclear-winter-1985
And Revkin's investigative report on the vanishing of Vladimir Alexandrov, a high-profile Soviet atmospheric scientist who'd become a fan of American cars and cuisine while visiting NCAR, a mountainside supercomputer lab in Colorado:
http://j.mp/alexandrovmissing
Here are emails showing exchanges between Dr. Will Happer, a senior Trump Administration science and security adviser, and the Heartland Institute -- which has long sought to cast doubt on the enormous body of science pointing to rising dangers from human emissions of climate-warming gases.
The emails were released under a Freedom of Information Act request by the Environmental Defense Fund: http://blogs.edf.org/climate411/files/2019/03/Climate-Review-FOIA-CEQ.pdf
Here's an Associated Press story:
https://www.apnews.com/4ec9affd55a345d582a4cc810686137e
EDF provided this copy to Andrew Revkin.
Here's an excerpt from a 2017 interview Revkin did with Happer for ProPublica: https://www.youtube.com/watch?v=MSpL5dziylo
A Physicist and Possible Adviser to Trump Describes His Love of Science, and CO2
https://www.propublica.org/article/a-physicist-and-possible-adviser-to-trump-describes-his-love-of-science-co2
More on Happer in National Geographic:
Does the U.S. need a ‘presidential climate security committee’?
A Trump adviser who sees rising CO2 as a good thing wants a panel to review government findings that climate change is a security threat.... https://www.nationalgeographic.com/environment/2019/02/trump-presidential-climate-security-committee/
This was the document leaked to the press this week ahead of a White House meeting assessing whether President Trump should create a committee to assess conclusions about links between global warming and national security.
Some Globo coverage in 1990 from the trial of the Alves family members and associates charged with the assassination of Chico Mendes in December 1988, including an interview with Andrew Revkin, who'd just published The Burning Season, a book chronicling Mendes's life, death and legacy. More: http://bit.ly/revkinmendes
An Island Magazine feature by Andy Revkin provided an intimate look at changes in a Polynesian family and village as modern life intruded in the 1980s.
This cover story on climate change by Andrew Revkin was published in Discover Magazine in October, 1988. For more on the article visit this Dot Earth post: 1988-2008: Climate Then and Now http://nyti.ms/WIvLbH via @dotearth
Make sure to click to the last page, which was the back-cover advertisement that month - for cigarettes.
Shows things can change, sometimes slowly.
And read Andy's reflection on lessons learned in 30 years of climate coverage:
http://j.mp/revkin30yearsclimate
Enhancing LPG Use During Pregnancya collaboration between KEM Health Research Center, Sri Ramachanda University, and University of California, Berkeley
An explanatory presentation provided to ProPublica.org
Lewis Reznik, who spent his adult life as a dentist in Westchester County, New York, had a very different adolescence - on the run between Nazis and Russian troops in Poland as the Holocaust unfolded. This is is remarkable memoir. Lew died in 2013.
I edited the manuscript and helped Lew publish the book.
Please purchase a copy at j.mp/boysholocaust
Share and discuss the book on Facebook: j.mp/boysholocaustFB
Context:
"Royal Dutch Shell in Nigeria: Where Do Responsibilities End?" Journal of Business Ethics, 2015
https://link.springer.com/article/10.1007/s10551-014-2142-7
Shell's plans for Nigeria (SPDC subsidiary), 2013: http://www.shell.com/media/news-and-media-releases/2013/spdc-sets-out-its-future-intent-for-nigeria.html
Business & Human Rights Resource Center on two landmark lawsuits:
https://business-humanrights.org/en/shell-lawsuit-re-nigeria-kiobel-wiwa
More from Earth Institute of Columbia University (20)
27052024_First India Newspaper Jaipur.pdfFIRST INDIA
Find Latest India News and Breaking News these days from India on Politics, Business, Entertainment, Technology, Sports, Lifestyle and Coronavirus News in India and the world over that you can't miss. For real time update Visit our social media handle. Read First India NewsPaper in your morning replace. Visit First India.
CLICK:- https://firstindia.co.in/
#First_India_NewsPaper
Welcome to the new Mizzima Weekly !
Mizzima Media Group is pleased to announce the relaunch of Mizzima Weekly. Mizzima is dedicated to helping our readers and viewers keep up to date on the latest developments in Myanmar and related to Myanmar by offering analysis and insight into the subjects that matter. Our websites and our social media channels provide readers and viewers with up-to-the-minute and up-to-date news, which we don’t necessarily need to replicate in our Mizzima Weekly magazine. But where we see a gap is in providing more analysis, insight and in-depth coverage of Myanmar, that is of particular interest to a range of readers.
01062024_First India Newspaper Jaipur.pdfFIRST INDIA
Find Latest India News and Breaking News these days from India on Politics, Business, Entertainment, Technology, Sports, Lifestyle and Coronavirus News in India and the world over that you can't miss. For real time update Visit our social media handle. Read First India NewsPaper in your morning replace. Visit First India.
CLICK:- https://firstindia.co.in/
#First_India_NewsPaper
31052024_First India Newspaper Jaipur.pdfFIRST INDIA
Find Latest India News and Breaking News these days from India on Politics, Business, Entertainment, Technology, Sports, Lifestyle and Coronavirus News in India and the world over that you can't miss. For real time update Visit our social media handle. Read First India NewsPaper in your morning replace. Visit First India.
CLICK:- https://firstindia.co.in/
#First_India_NewsPaper
role of women and girls in various terror groupssadiakorobi2
Women have three distinct types of involvement: direct involvement in terrorist acts; enabling of others to commit such acts; and facilitating the disengagement of others from violent or extremist groups.
Future Of Fintech In India | Evolution Of Fintech In IndiaTheUnitedIndian
Navigating the Future of Fintech in India: Insights into how AI, blockchain, and digital payments are driving unprecedented growth in India's fintech industry, redefining financial services and accessibility.
03062024_First India Newspaper Jaipur.pdfFIRST INDIA
Find Latest India News and Breaking News these days from India on Politics, Business, Entertainment, Technology, Sports, Lifestyle and Coronavirus News in India and the world over that you can't miss. For real time update Visit our social media handle. Read First India NewsPaper in your morning replace. Visit First India.
CLICK:- https://firstindia.co.in/
#First_India_NewsPaper
हम आग्रह करते हैं कि जो भी सत्ता में आए, वह संविधान का पालन करे, उसकी रक्षा करे और उसे बनाए रखे।" प्रस्ताव में कुल तीन प्रमुख हस्तक्षेप और उनके तंत्र भी प्रस्तुत किए गए। पहला हस्तक्षेप स्वतंत्र मीडिया को प्रोत्साहित करके, वास्तविकता पर आधारित काउंटर नैरेटिव का निर्माण करके और सत्तारूढ़ सरकार द्वारा नियोजित मनोवैज्ञानिक हेरफेर की रणनीति का मुकाबला करके लोगों द्वारा निर्धारित कथा को बनाए रखना और उस पर कार्यकरना था।
ys jagan mohan reddy political career, Biography.pdfVoterMood
Yeduguri Sandinti Jagan Mohan Reddy, often referred to as Y.S. Jagan Mohan Reddy, is an Indian politician who currently serves as the Chief Minister of the state of Andhra Pradesh. He was born on December 21, 1972, in Pulivendula, Andhra Pradesh, to Yeduguri Sandinti Rajasekhara Reddy (popularly known as YSR), a former Chief Minister of Andhra Pradesh, and Y.S. Vijayamma.
In a May 9, 2024 paper, Juri Opitz from the University of Zurich, along with Shira Wein and Nathan Schneider form Georgetown University, discussed the importance of linguistic expertise in natural language processing (NLP) in an era dominated by large language models (LLMs).
The authors explained that while machine translation (MT) previously relied heavily on linguists, the landscape has shifted. “Linguistics is no longer front and center in the way we build NLP systems,” they said. With the emergence of LLMs, which can generate fluent text without the need for specialized modules to handle grammar or semantic coherence, the need for linguistic expertise in NLP is being questioned.
‘वोटर्स विल मस्ट प्रीवेल’ (मतदाताओं को जीतना होगा) अभियान द्वारा जारी हेल्पलाइन नंबर, 4 जून को सुबह 7 बजे से दोपहर 12 बजे तक मतगणना प्रक्रिया में कहीं भी किसी भी तरह के उल्लंघन की रिपोर्ट करने के लिए खुला रहेगा।
New Climate Change Statement from the American Meteorological Society
1. Climate Change
An Information Statement of the American Meteorological Society
(Adopted by AMS Council 20 August 2012)
The following is an AMS Information Statement intended to provide a trustworthy, objective,
and scientifically up-to-date explanation of scientific issues of concern to the public at large.
Background
This statement provides a brief overview of how and why global climate has changed over the
past century and will continue to change in the future. It is based on the peer-reviewed scientific
literature and is consistent with the vast weight of current scientific understanding as expressed
in assessments and reports from the Intergovernmental Panel on Climate Change, the U.S.
National Academy of Sciences, and the U.S. Global Change Research Program. Although the
statement has been drafted in the context of concerns in the United States, the underlying issues
are inherently global in nature.
How is climate changing?
Warming of the climate system now is unequivocal, according to many different kinds of
evidence. Observations show increases in globally averaged air and ocean temperatures, as well
as widespread melting of snow and ice and rising globally averaged sea level. Surface
temperature data for Earth as a whole, including readings over both land and ocean, show an
increase of about 0.8°C (1.4°F) over the period 1901–2010 and about 0.5°C (0.9°F) over the
period 1979–2010 (the era for which satellite-based temperature data are routinely available).
Due to natural variability, not every year is warmer than the preceding year globally.
Nevertheless, all of the 10 warmest years in the global temperature records up to 2011 have
occurred since 1997, with 2005 and 2010 being the warmest two years in more than a century of
global records. The warming trend is greatest in northern high latitudes and over land. In the
U.S., most of the observed warming has occurred in the West and in Alaska; for the nation as a
whole, there have been twice as many record daily high temperatures as record daily low
temperatures in the first decade of the 21st century.
The effects of this warming are especially evident in the planet’s polar regions. Arctic sea ice
extent and volume have been decreasing for the past several decades. Both the Greenland and
Antarctic ice sheets have lost significant amounts of ice. Most of the world’s glaciers are in
retreat.
Other changes, globally and in the U.S., are also occurring at the same time. The amount of rain
falling in very heavy precipitation events (the heaviest 1% of all precipitation events) has
1
2. increased over the last 50 years throughout the U.S. Freezing levels are rising in elevation, with
rain occurring more frequently instead of snow at mid-elevations of western mountains. Spring
maximum snowpack is decreasing, snowmelt occurs earlier, and the spring runoff that supplies
over two-thirds of western U.S. streamflow is reduced. Evidence for warming is also observed in
seasonal changes across many areas, including earlier springs, longer frost-free periods, longer
growing seasons, and shifts in natural habitats and in migratory patterns of birds and insects.
Globally averaged sea level has risen by about 17 cm (7 inches) in the 20th century, with the rise
accelerating since the early 1990s. Close to half of the sea level rise observed since the 1970s has
been caused by water expansion due to increases in ocean temperatures. Sea level is also rising
due to melting from continental glaciers and from ice sheets on both Greenland and Antarctica.
Locally, sea level changes can depend also on other factors such as slowly rising or falling land,
which results in some local sea level changes much larger or smaller than the global average.
Even small rises in sea level in coastal zones are expected to lead to potentially severe impacts,
especially in small island nations and in other regions that experience storm surges associated
with vigorous weather systems.
Why is climate changing?
Climate is always changing. However, many of the observed changes noted above are beyond
what can be explained by the natural variability of the climate. It is clear from extensive
scientific evidence that the dominant cause of the rapid change in climate of the past half century
is human-induced increases in the amount of atmospheric greenhouse gases, including carbon
dioxide (CO2), chlorofluorocarbons, methane, and nitrous oxide. The most important of these
over the long term is CO2, whose concentration in the atmosphere is rising principally as a result
of fossil-fuel combustion and deforestation. While large amounts of CO2 enter and leave the
atmosphere through natural processes, these human activities are increasing the total amount in
the air and the oceans. Approximately half of the CO2 put into the atmosphere through human
activity in the past 250 years has been taken up by the ocean and terrestrial biosphere, with the
other half remaining in the atmosphere. Since long-term measurements began in the 1950s, the
atmospheric CO2 concentration has been increasing at a rate much faster than at any time in the
last 800,000 years. Having been introduced into the atmosphere it will take a thousand years for
the majority of the added atmospheric CO2 to be removed by natural processes, and some will
remain for thousands of subsequent years.
Water vapor also is an important atmospheric greenhouse gas. Unlike other greenhouse gases,
however, the concentration of water vapor depends on atmospheric temperature and is controlled
by the global climate system through its hydrological cycle of evaporation-condensation-
precipitation. Water vapor is highly variable in space and time with a short lifetime, because of
weather variability. Observations indicate an increase in globally averaged water vapor in the
atmosphere in recent decades, at a rate consistent with the response produced by climate models
that simulate human-induced increases in greenhouse gases. This increase in water vapor also
2
3. strengthens the greenhouse effect, amplifying the impact of human-induced increases in other
greenhouse gases.
Human activity also affects climate through changes in the number and physical properties of
tiny solid particles and liquid droplets in the atmosphere, known collectively as atmospheric
aerosols. Examples of aerosols include dust, sea salt, and sulfates from air pollution. Aerosols
have a variety of climate effects. They absorb and redirect solar energy from the sun and thermal
energy emitted by Earth, emit energy themselves, and modify the ability of clouds to reflect
sunlight and to produce precipitation. Aerosols can both strengthen and weaken greenhouse
warming, depending on their characteristics. Most aerosols originating from human activity act
to cool the planet and so partly counteract greenhouse gas warming effects. Aerosols lofted into
the stratosphere [between about 13 km (8 miles) and 50 km (30 miles) altitude above the surface]
by occasional large sulfur-rich volcanic eruptions can reduce global surface temperature for
several years. By contrast, carbon soot from incomplete combustion of fossil fuels warms the
planet, so that decreases in soot would reduce warming. Aerosols have lifetimes in the
troposphere [at altitudes up to approximately 13 km (8 miles) from the surface in the middle
latitudes] on the order of one week, much shorter than that of most greenhouse gases, and their
prevalence and properties can vary widely by region.
Land surface changes can also affect the surface exchanges of water and energy with the
atmosphere. Humans alter land surface characteristics by carrying out irrigation, removing and
introducing forests, changing vegetative land cover through agriculture, and building cities and
reservoirs. These changes can have significant effects on local-to-regional climate patterns,
which adds up to a small impact on the global energy balance as well.
How can climate change be projected into the future?
Factors that have altered climate throughout history, both human (such as human emission of
greenhouse gases) and natural (such as variation of the Sun’s energy emission, the Earth’s orbit
about the Sun, and volcanic eruptions), will continue to alter climate in the future. Climate
projections for decades into the future are made using complex numerical models of the climate
system that account for changes in the flow of energy into and out of the Earth system on time
scales much longer than the predictability limit (of about two weeks) for individual weather
systems. The difference between weather and climate is critically important in considering
predictability. Climate is potentially predictable for much longer time scales than weather for
several reasons. One reason is that climate can be meaningfully characterized by seasonal-to-
decadal averages and other statistical measures, and the averaged weather is more predictable
than individual weather events. A helpful analogy in this regard is that population averages of
human mortality are predictable while life spans of individuals are not. A second reason is that
climate involves physical systems and processes with long time scales, including the oceans and
snow and ice, while weather largely involves atmospheric phenomena (e.g., thunderstorms,
intense snow storms) with short time scales. A third reason is that climate can be affected by
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4. slowly changing factors such as human-induced changes in the chemical composition of the
atmosphere, which alter the natural greenhouse effect.
Climate models simulate the important aspects of climate and climate change based on
fundamental physical laws of motion, thermodynamics, and radiative transfer. These models
report on how climate would change in response to several specific “scenarios” for future
greenhouse gas emission possibilities. Future climate change projections have uncertainties that
occur for several reasons — because of differences among models, because long-term
predictions of natural variations (e.g., volcanic eruptions and El Niño events) are not possible,
and because it is not known exactly how greenhouse gas emissions will evolve in future decades.
Future emissions will depend on global social and economic development, and on the extent and
impact of activities designed to reduce greenhouse gas and black carbon emissions.
Changes in the means and extremes of temperature and precipitation in response to increasing
greenhouse gases can be projected over decades to centuries into the future, even though the
timing of individual weather events cannot be predicted on this time scale. Because it would take
many years for observations to verify whether a future climate projection is correct, researchers
establish confidence in these projections by using historical and paleoclimate evidence and
through careful study of observations of the causal chain between energy flow changes and
climate-pattern responses. A valuable demonstration of the validity of current climate models is
that when they include all known natural and human-induced factors that influence the global
atmosphere on a large scale, the models reproduce many important aspects of observed changes
of the 20th-century climate, including (1) global, continental, and subcontinental mean and
extreme temperatures, (2) Arctic sea ice extent, (3) the latitudinal distribution of precipitation,
and (4) extreme precipitation frequency.
Model limitations include inadequate representations of some important processes and details.
For example, a typical climate model does not yet treat fully the complex dynamical, radiative,
and microphysical processes involved in the evolution of a cloud or the spatially variable nature
of soil moisture, or the atmospheric interactions with the biosphere. Nevertheless, in spite of
these limitations, climate models have demonstrated skill in reproducing past climates, and they
agree on the broad direction of future climate.
How is the climate expected to change in the future?
Future warming of the climate is inevitable for many years due to the greenhouse gases already
added to the atmosphere and the heat that has been taken up by the oceans. Amelioration might
be possible through devising and implementing environmentally responsible geoengineering
approaches, such as capture and storage measures to remove CO2 from the atmosphere.
However, the potential risks of geoengineering may be quite large, and more study of the topic
(including other environmental consequences) is needed. The subject of geoengineering is
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5. outside the scope of this statement (for more information see AMS Statement on
Geoengineering).
In general, many of the climate-system trends observed in recent decades are projected to
continue. Those projections, and others in this section, are largely based on simulations
conducted with climate models, and assume that the amount of greenhouse gas in the atmosphere
will continue to increase due to human activity. Global efforts to slow greenhouse gas emissions
have been unsuccessful so far. However, were future technologies and policies able to achieve a
rapid reduction of greenhouse gas emissions — an approach termed “mitigation” — this would
greatly lessen future global warming and its impacts.
Confidence in the projections is higher for temperature than for other climate elements such as
precipitation, and higher at the global and continental scales than for the regional and local
scales. The model projections show that the largest warming will occur in northern polar regions,
over land areas, and in the winter season, consistent with observed trends.
In the 21st century, global sea level also will continue to rise although the rise will not be uniform
at all locations. With its large mass and high capacity for heat storage, the ocean will continue to
slowly warm and thus thermally expand for several centuries. Model simulations project about
27 cm (10 inches) to 71 cm (28 inches) of global sea level rise due to thermal expansion and
melting of ice in the 21st century. Moreover, paleoclimatic observations and ice-sheet modeling
indicate that melting of the Greenland and the West Antarctic ice sheets will eventually cause
global sea level to rise several additional meters by 2500 if warming continues at its present rate
beyond the 21st century.
Atmospheric water content will increase globally, consistent with warmer temperatures, and
consequently the global hydrological cycle will continue to accelerate. For many areas, model
simulations suggest there will be a tendency towards more intense rain and snow events
separated by longer periods without precipitation. However, changes in precipitation patterns are
expected to differ considerably by region and by season. In some regions, the accelerated
hydrological cycle will likely reinforce existing patterns of precipitation, leading to more severe
droughts and floods. Further poleward, the greater warming at high latitudes and over land likely
will change the large-scale atmospheric circulation, leading to significant regional shifts in
precipitation patterns. For example, the model simulations suggest that precipitation will increase
in the far northern parts of North America, and decrease in the southwest and south-central
United States where more droughts will occur.
Climate-model simulations further project that heavy precipitation events will continue to
become more intense and frequent, leading to increased precipitation totals from the strongest
storms. This projection has important implications for water-resource management and flood
control. The simulations also indicate the likelihood of longer dry spells between precipitation
events in the subtropics and lower-middle latitudes, with shorter dry spells projected for higher
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6. latitudes where mean precipitation is expected to increase. Continued warming also implies a
reduction of winter snow accumulations in favor of rain in many places, and thus a reduced
spring snowpack. Rivers now fed by snowmelt will experience earlier spring peaks and reduced
warm-season flows. Widespread retreat of mountain glaciers is expected to eventually lead to
reduced dry season flows for glacier-fed rivers. Drought is projected to increase over Africa,
Europe, and much of the North American continental interior, and particularly the southwest
United States. However, natural variations in world ocean conditions at decadal scale, such as
those in the North Pacific and North Atlantic basins, could offset or enhance such changes in the
next few decades. For the longer term, paleoclimatic observations suggest that droughts lasting
decades are possible and that these prolonged droughts could occur with little warning.
Weather patterns will continue to vary from day to day and from season to season, but the
frequency of particular patterns and extreme weather and climate events may change as a result
of global warming. Model simulations project an increased proportion of global hurricanes that
are in the strongest categories, namely 4 and 5 on the Saffir-Simpson scale, although the total
counts of hurricanes may not change or may even decrease. Some regional variations in these
trends are possible. Simulations also indicate that midlatitude storm tracks will shift poleward.
Interannual variations of important large-scale climate conditions (such as El Niño and La Niña)
will also continue to occur, but there may be changes in their intensity, frequency, and other
characteristics, resulting in different responses by the atmosphere. Heat waves and cold snaps
and their associated weather conditions will continue to occur, but proportionately more extreme
warm periods and fewer cold periods are expected. Indeed, what many people traditionally
consider a cold wave is already changing toward less severe conditions. Frost days (those with
minimum temperature below freezing) will be fewer and growing seasons longer. Drier
conditions in summer, such as those anticipated for the southern United States and southern
Europe, are expected to contribute to more severe episodes of extreme heat. Critical thresholds of
daily maximum temperature, above which ecosystems and crop systems (e.g., food crops such as
rice, corn, and wheat) suffer increasingly severe damage, are likely to be exceeded more
frequently.
The Earth system is highly interconnected and complex, with many processes and feedbacks that
only slowly are becoming understood. In particular, the carbon cycle remains a large source of
uncertainty for the projection of future climate. It is unclear if the land biosphere and oceans will
be able to continue taking up carbon at their current rate into the future. One unknown is whether
soil and vegetation will become a global source rather than a sink of carbon as the planet warms.
Another unknown is the amount of methane that will be released due to high-latitude warming.
There are indications that large regions of the permafrost in parts of Alaska and other northern
polar areas are already thawing, with the potential to release massive amounts of carbon into the
atmosphere beyond those being directly added by human activity. The portion of the increased
CO2 release that is absorbed by the world ocean is making the ocean more acidic, with negative
implications for shell- and skeleton-forming organisms and more generally for ocean
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