Human-induced climate change is a reality. Not only in the remote polar regions or for small islands in distant oceans, but here in our own backyards. Climate change is not just a problem for the future. It’s happening now, and we’re beginning to see its effects on our lives. Humans are responsible, and our actions will determine the extent of future climate change and the severity of its impacts. It’s not too late. Decisions made now will determine whether we get big changes or smaller ones. Substantially cutting heat-trapping emissions will result in less climate change and smaller impacts. Earlier cuts in emissions would have a greater effect than cuts made later. A key finding of this report is that climate change is happening NOW. We’re already observing changes in many aspects of climate. And we’ve documented these changes. U.S. average temperature has risen by 1.5 degrees Fahrenheit over the last 50 years. We’ve had more rain coming in heavy downpours that can cause flooding. Less winter precipitation is falling as snow and more as rain. So there’s less snowpack in the mountains, and it melts earlier in spring. These changes alter the amounts and timing of river flows, making less water available in summer. Last, but certainly not least, sea level has risen along U.S. coastlines. Some places are seeing much greater rises than others – and similar regional differences are expected in the future. And there are other changes we’ve observed. For example, glaciers in the mountain West and in Alaska are melting, and permafrost is thawing. Not only have these changes been observed and documented in the U.S., every one of them has been shown to be linked to human activities – namely the increase in heat-trapping gases caused by burning fossil fuels like coal, oil, and gas. Across the country, the growing season is about two weeks longer, primarily due to spring arriving earlier than it used to. Now, that may sound like a good thing, and in some ways it is. There are both positive and negative effects of many of these changes. But, overall, most impacts will be negative. This is true partly because we’ve designed and built our infrastructure for the climate we’ve HAD, not necessarily for the climate we’re GOING to have. For example, we’ve designed our water systems for temperature and precipitation patterns of the past century, and those patterns are now changing. We’ve built our coastal cities along the existing shoreline, not anticipating sea level to rise several feet in this century. Another reason most of the changes will be detrimental is because of the RATE of change. If climate changes slowly, there’s a better chance that society and natural systems can adapt. But climate is now changing at an unnaturally rapid rate, and the projections are for EVEN MORE RAPID change, if heat-trapping emissions are not curtailed. This briefing will guide you through some of the kinds of climate changes and resulting impacts we’re seeing in the United States, and what’s in store for our future.
Jack Kaye - Acting Chair, SGCR / Acting Director , USGCRP
Global Change Research Act of 1990 (P.L. 101-606) "a comprehensive and integrated United States research program which will assist the Nation and the world to understand, assess, predict, and respond to human-induced and natural processes of global change.“
To improve understanding of uncertainties in climate science
To expand global observing systems
To develop science-based resources to support policymaking and resource management
To communicate findings broadly among scientific and stakeholder communities