In late November, the federal government released its Fourth National Climate Assessment. The report represents a summary of the most up-to-date climate science and is authored by scientists from 13 federal agencies. The report’s conclusions closely track the conclusions of the vast majority of peer-reviewed science regarding human-driven climate change. Four main takeaways from the report are:

Climate change is already happening. The impacts of climate change are already being felt across the country. More frequent and intense weather and climate-related events - like drought, tropical storms, wildfires, and flooding - are affecting communities across the United States today and damaging our infrastructure and natural resources.

Climate change is going to get worse. Even with a significant reduction of greenhouse gas emissions in the future, many of the effects of climate change and sea-level rise will still occur because of the damage already done to the atmosphere. The number of communities dealing with sea-level rise is going to increase by the middle of this century.

Climate change is going to cost Americans dearly. Because climate change will adversely affect our economy, public health, and natural resources, the negative economic impacts will be substantial. Projections for continued growth of greenhouse gas emissions at historic rates (i.e., if we do nothing to curb emissions) forecast economic losses reaching hundreds of billions of dollars by the end of this century - more than the gross domestic product (GDP) of many U.S. states.

Impacts will be interconnected. For example, damage to energy-related infrastructure in Louisiana and Texas will drive up energy costs. The worst impacts will affect disadvantaged populations that do not have the resources to implement adaptation measures - such as elevating structures to counter increased flooding or sea-level rise - and are not able to absorb increasing costs.

We can still do something about climate change. Many of the worst impacts of climate change can be avoided or mitigated with adaptation and aggressive reductions in greenhouse gas emissions.

Future risks are largely dependent on decisions made today. This assessment shows that more substantial reductions in greenhouse gas emissions are needed to avoid the most severe consequences in the long term. Adaptation actions that counter the effects of climate change, such as flood plain restoration, can help mitigate the worst impacts while providing additional benefits such as improved air quality, restored ecosystems, and increased community vitality.

The findings of this report are sobering and they reinforce what scientists and many Americans have observed for decades.

Congress is likely to focus more intensively on the range of policy options that can reduce emissions, store carbon, and protect people and communities from the near-term impacts of a warming climate and rising seas. Policy options include tax and other incentives for renewable energy development, further limiting emissions from power plants and vehicles, and promoting carbon storage in the soil.

The League will be closely following this debate. The threats to people, communities, natural resources, and outdoor recreation are clear. League members have adopted conservation policies that will provide useful guidance in evaluating congressional proposals. For example, member-adopted policy supports a rapid transition to renewable sources of energy; dramatically improving the energy efficiency of vehicles, the power grid, homes and buildings, and consumer products; and developing new technology to more effectively and efficiently store and distribute electricity generated by wind and solar.