The Environmental and Energy Study Institute (EESI), Union of Concerned Scientists (UCS), and National Wildlife Federation (NWF) held a briefing on the latest climate change findings, as reported by leading scientists in the 4th National Climate Assessment (NCA) and the Intergovernmental Panel on Climate Change’s (IPCC) Special Report. Attendees learned about how climate change is expected to affect the United States and how federal, state, and local governments can reduce greenhouse gas emissions and help communities adapt to rapidly encroaching risks over the next decade and beyond. They learned how Congressional districts are being impacted by climate change, and how they could benefit from investing in low-carbon solutions and advance planning to safeguard lives, infrastructure, and businesses.




Senator Tom Carper (D-DE)

  • The effects of human activity on climate have been visible for a while now, and are readily apparent in the Senator’s state of Delaware (the lowest-lying state in the nation), where sea level rise combined with sinking land is causing frequent flooding events.
  • There is no Plan(et) B, so we have to act to help the planet we’re on.
  • We can create jobs while addressing climate change head on. But we can’t just take away jobs from coal miners and others working in the fossil fuel industry. There is ample opportunity in clean energy and energy conservation for job creation. “In adversity lies opportunity.”
  • It’s possible to have better air, water, and public health while creating jobs. It’s in the best interest of the economy and it is our moral responsibility.


Collin O’Mara, President and Chief Executive Officer, National Wildlife Federation

  • Now is the time to take the words off the page and translate that into actions and solutions.
  • The IPCC report calls for a rapid and far-reaching transformation of the global economy.
  • Right now is an opportunity to translate science into policy.


Dr. David Easterling, Chief, Observations and Data Records, and Director, National Climate Assessment Technical Support Unit, Center for Weather and Climate, National Oceanic and Atmospheric Administration (NOAA)'s National Centers for Environmental Information

  • Globally, 2018 was the fourth warmest year on record, and six of the hottest years have occurred in the past decade. These temperature increases correlate directly with increases in greenhouse gas emissions (GHGs). The increase in GHGs is directly related to the burning of fossil fuels.
  • The most warming has taken place in colder regions, such as Alaska, Canada, Greenland, and Russia. There is not enough data to determine temperature trends in the Arctic and Antarctic.
  • We are seeing the consequences of global warming right now on a global scale, with the loss of Arctic sea ice and rising sea levels. Sea levels have risen nearly 10 inches since the 1920s, already leading to major impacts around the world, including in the United States. ‘Nuisance floods’ (also known as ‘sunny day floods’) have increased five-to-ten fold since the 1960s in major U.S. cities, including Boston and Miami. This has major economic impacts as cities work to drain flood waters and mitigate damage.
  • The average global temperature has increased 1.5 degrees Fahrenheit since the beginning of the 20th century. This rise in temperature has affected growing seasons. Because warmer air can hold more water vapor, rising temperatures also have caused a rise in precipitation, which results in worse storms and more flooding events.
  • Why are we confident that human emissions of greenhouse gases are the dominant cause of warming? Climate models including only natural forcing factors (solar, orbital, volcanic) do not show the warming we are experiencing today. When we add in human influences (greenhouse gases, ozone, land cover) the models align perfectly with observed warming.


Dr. Katharine Hayhoe, Director, The Climate Science Center at Texas Tech University

  • The National Climate Assessment is divided into two volumes. Volume 1 is the most comprehensive and up-to-date assessment of climate science in the world. The report was compiled by more than 50 authors from 12 federal agencies, and comes to almost 500 pages. It was reviewed twice by relevant federal agencies, and was subject to public and National Academy review. The National Academy review was carried out by a special panel of independent experts. The review itself was over 100 pages long, and researchers had to respond to every single comment. The IPCC report has been one of the most thoroughly reviewed and transparent scientific reports ever.
  • Volume 1 assesses the science of climate change and tells us that: (1) climate change is real, (2) it’s caused by us, and (3) it’s serious. The window of time to prevent widespread dangerous impacts is closing fast.
  • According to Dr. Hayhow, “We have now elbowed natural cycles out of the driver’s seat… We are driving this planet into the future and it is our choices that determine the future of the planet as well as how sensitive the planet is to the unprecedented experiment that we are conducting with it.”
  • The last time CO2 was at current levels of 400ppm was about three million years ago (before humans existed), at a time when the global average temperature and sea levels were significantly higher than today. Continued growth in CO2 emissions would lead to an atmospheric concentration not experienced in tens of millions of years, and present-day emission rates suggest there is no climate analog for the century in at least the last 100 million years.
  • Most people don’t have a problem with the science that explains why climate is changing—the problem is that people don’t believe it will harm them personally.
  • Volume 2 of the National Climate Assessment assesses climate impacts, risks, and the adaptation taking place in the United States. It had 350 authors across 12 federal agencies and is over 1,600 pages long. It tells us that climate change isn’t a distant issue, it affects every single one of us, and the more the climate changes, the more serious and dangerous the impacts will become.
  • The frequency and severity of extreme high temperature events are virtually certain to increase and extreme precipitation events are very likely to increase. Climate models tend to underestimate the observed trends—especially when it comes to the increase in extreme precipitation events.
  • Climate change is a threat multiplier. Climate change isn’t just creating new extreme weather events, it exacerbates the risks we see today: hurricanes are stronger, bigger, and slower; the frequency and severity of land-falling “atmospheric rivers" on the U.S. West Coast will increase; wildfires are larger, hotter, and burn longer. Climate change is loading the dice against us.


Dr. Brenda Ekwurzel, Director of Climate Science, Union of Concerned Scientists

  • Mitigation-related activities are already occurring in the United States at the federal, state, and local levels as well as in the private sector.
  • In the absence of more significant global mitigation efforts, climate change is projected to impose substantial damages on the U.S. economy and human health.
  • The IPCC considers four scenarios: a no-emissions scenario, which would have to have started five years ago; a low-emissions scenario, in which we emit at levels much lower than current levels; observed emissions; and a high-emissions scenario (that we’re on track to) which results in a temperature increase of more than 4 degrees Celsius above pre-industrial levels.
  • We must work on equitable solutions that are good for everyone. Solutions that fix a problem for one community and add problems to another are not viable solutions.
  • We are currently at +1 degree Celsius over pre-industrial temperatures. On our current track, we are set to reach +1.5 degrees Celsius by 2045, and +2 degrees Celsius by 2065.
  • Labor will likely be the most impacted sector. Currently, we are on track to see damages of $100 billion annually. On a low-emissions track, we could cut this by 48 percent. Damages in the second top sector—extreme temperature mortality—are currently on track to reach $100 billion annually, which could be reduced by 58 percent in a low-emissions scenario. Damages to coastal property, again at over $100 billion annually, would see reductions of 23 percent under a low-emissions scenario.
  • We must reduce our greenhouse gas emissions to net-zero (or below!) by mid-century to escape the worst effects of climate change.
  • Mitigation and adaptation are complementary—this complementarity is especially important given that a certain degree of climate change due to past and present emissions is unavoidable.


The NCA is a comprehensive report produced every four years by the U.S. Global Change Research Program, as required by Congress. The fourth edition of the report, released in November 2018, analyzes the effects of climate change across the country, including agriculture, energy production and use, land and water resources, transportation, and biodiversity. The NCA applies these findings to 10 regions across the United States and features recommendations on how to reduce risks associated with climate change to protect public health, economic sectors, and the environment. The report was crafted with policy-makers, utility and natural resource managers, public health officials, and emergency planners in mind.

The IPCC’s Special Report delves into the potential impacts of global warming under different greenhouse gas emission scenarios. The landmark report, released in October 2018, is the product of thousands of expert and government reviewers, more than 6,000 scientific references, and 91 authors and editors from 40 countries working under the banner of the United Nations. The report found that in order to keep global warming from crossing the critical 1.5 degrees Celsius threshold, a “rapid and far-reaching” transformation of the global economy would be necessary, including land and energy use, transportation, buildings, and industry.