Ecology is the scientific study of relationships between organisms and their environments. An ecosystem is a dynamic system of plant, animal, and microorganism communities interacting with each other and their non-living environment. Ecosystems and their services are affected directly and indirectly by climate change. Increased CO2 can directly increase plant productivity through CO2 fertilization but decreases transpiration, while indirect effects on climate patterns impact ecosystems. Different plant types like C3, C4, and CAM plants respond differently to increased CO2 due to differences in their photosynthetic pathways.

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2.  Ecology is the scientific study of relationships
in the natural world. It includes relationships
between organisms and their physical
environments (physiological ecology); between
organisms of the same species (population
ecology); between organisms of different
species (community ecology); and between
organisms and the fluxes of matter and energy
through biological systems (ecosystem
ecology).

3.  An ecosystem is a dynamic complex system of
plant, animal, and microorganism communities
and the non-living environment interacting
with each other as a functional unit.

4.  Ecosystems and ecosystem services affected by global climate change,
both directly and indirectly. Many studies particularly on agricultural
crops and forest shows that the enhanced atmospheric CO2 directly
increase productivity, because higher ambient CO2 concentration
stimulates net photosynthetic activity which have been called ´CO2-
fertilization` effect.
Transpiration decreases through a partial stomatal closure resulting in
increased water use efficiency of plants at least at a leaf scale;
nevertheless, there are considerable differences
between different species regarding their response. Some species in
terrestrial ecosystems may in the long-term indirectly react negatively,
perhaps fatal, to increased CO2 concentration. The
indirect responses of ecosystems are due to the effect of elevated CO2
concentration is through effect on climate, such as change in temperature
or radiation, humidity, precipitation or other
climate variables.

5.  Different processes in plants or forest ecosystems
and their interaction with climate variability
is complex, due to different response of physical,
biological, and chemical processes. An
increase in the ambient CO2 concentration could
reduce the opening of stomata required to
allow a given amount of CO2 to enter in the plant
that might reduce transpiration of the trees.

6. 
Plants are grouped in to ´C3`, ´C4` and ´plants according to their
photosynthetic metabolic pathways. Around 95 % of the world
plant biomass grouped in ´C3` plant species (e.g. wheat,
rice, fruits & vegetables), C4 (e.g. maize or corn, sugarcane &
sorghum) and CAM (e. g. Pineapple). These divisions into
groups largely based on the enzymes involved in photosynthetic
fixation of CO2, namely Rubisco, PEP carboxylase and to some
extent carbonic anhydrase, which are significantly different in
their response to CO2 enrichment. CO2 together with other
minerals
can activate Rubisco by binding at a non-catalytic site on the
enzyme protein. The process of
photorespiration rate is high in C3 plants and the relative
proportion of CO2 and O2 inside the
leaf determines the rate of photorespiration. In contrast, PEP
carboxylase in C4 plants not
inhibited by O2 and thus photorespiration is negligible.

7.  The crops that we grow for food need specific
conditions to thrive, including the right
temperature and enough water. A changing
climate could have both positive and negative
effects on crops. For example, the northern parts of
the United States have generally cool
temperatures, so warmer weather could help
certain crops grow. In southern areas where
temperatures are already hot, even more heat
could hurt crop growth. Global climate change will
also affect agriculture and food supply in many
other ways.

8.  Forests provide homes for many kinds of
plants and animals. They also protect water
quality, offer opportunities for recreation, and
provide people with wood. Forests are
sensitive to many effects of climate change,
including shifting weather patterns, drought,
wildfires, and the spread of pests like the
mountain pine beetle. Unlike some animals,
trees can't just get up and move when the
temperature gets too hot or other conditions
change!

9.  Most plants and animals live in areas with very specific
climate conditions, such as temperature and rainfall
patterns, that enable them to thrive. Any change in the
climate of an area can affect the plants and animals living
there, as well as the makeup of the entire ecosystem. Some
species are already responding to a warmer climate by
moving to cooler locations. For example, some North
American animals and plants are moving farther north or to
higher elevations to find suitable places to live. Climate
change also alters the life cycles of plants and animals. For
example, as temperatures get warmer, many plants are
starting to grow and bloom earlier in the spring and survive
longer into the fall. Some animals are waking from
hibernation sooner or migrating at different times, too.
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