Global average sea level has risen about 8 inches since 1900, driven by expansion of the warming ocean, melting of mountain glaciers, and losses from the Greenland and Antarctic ice sheets. This rise has caused coastal cities to see an uptick in flooding, both during storms and as “sunny-day” flooding from tides alone. These flooding events disrupt economies, make it difficult to deliver emergency services, and disproportionately affect older, infirm, and low socioeconomic status populations.
Check out our video on Sea-Level Rise for the Coasts of California, Oregon, and Washington.
Climate change is leading to more extreme weather of certain types—especially those types of weather events related to temperature. Warming due to climate change is leading to more heat waves, and extremely hot days and nights have become more likely. Extreme cold events are less frequent and less severe than in previous decades. Climate change is also leading to more heavy rainfall and snowfall events as Earth’s atmosphere is becoming warmer and moister. Climate change can exacerbate droughts, as increased surface temperature increases evaporation, which leaves the land drier than it would be at a cooler temperature. Hurricanes (when they occur) will be more intense, produce more rainfall, and possibly be larger. In addition, rising sea level contributes to stronger storm surges.
Warming and precipitation changes are altering the geographical ranges of many plant and animal species and the timing of their life cycles. For example, terrestrial species sensitive to hot temperatures are shifting their ranges to be further poleward or at higher elevation. Changes in climate conditions have allowed invasive species to spread more easily, sometimes causing unprecedented changes in ecosystems. In other cases, species are migrating or blossoming at unusual times, which has affected how species interact with each other.
Key resources: Abrupt Climate Change: Anticipating Surprises
Oceans are warming and becoming more acidic, harming corals and other marine life. Increasing changes in the global climate and ocean chemistry threaten the persistence of coral reefs. The link between temperature and corals derives largely from the bleaching response of corals to higher than normal temperatures. Recent increases in ocean temperature have led to a significant increase in exposure of corals to high temperature events and have caused severe coral loss globally. Additionally, CO2 from fossil fuel combustion forms carbonic acid when it dissolves in the ocean, gradually making the oceans more acidic which reduces growth rates of coral.
Key resources: A Decision Framework for Interventions to Increase the Persistence and Resilience of Coral Reefs; A Research Review of Interventions to Increase the Persistence and Resilience of Coral Reefs; Sustaining Ocean Observations to Understand Future Changes in Earth's Climate; Ocean Acidification: Starting with the Science; Ocean Acidification: A National Strategy to Meet the Challenges of a Changing Ocean
Abrupt changes—also known as tipping points—have been previously observed in the climate system and are underway today. The climate system involves many competing processes that could switch the climate into a different state once a threshold has been exceeded. In addition, gradual climate changes can cross thresholds in both natural systems and human systems, leading to abrupt impacts. Disappearance of late-summer Arctic Sea Ice and increases in extinction threat for marine and terrestrial species are abrupt changes underway today. In addition, there is increasing concern about the possible destabilization of the West Antarctic Ice Sheet, which would lead to more rapid sea level rise.
Some future climate change is unavoidable, necessitating steps to adapt to current and anticipated impacts. Many of the things people use or do every day—from roads to farms, buildings to subways, jobs to recreational activities—were optimized for the climate of the 19th and 20th centuries. They were built with the assumption of certain temperature ranges, precipitation patterns, frequency of extreme events, and other manifestations of climate, which are now shifting. Even if humankind were to succeed in limiting global climate change in accordance with current goals, adaptation will be needed to protect people, ecosystems, infrastructure, and cultural resources from the impacts of climate change, many of which are already evident.
Appropriate measures to adapt to climate change will vary from location to location. In some places, incremental steps will be sufficient to manage risk over the next several decades. In other places, transformational changes, such as relocation, are likely to be required. Adaptation strategies range from technological and engineered solutions to social, economic, and institutional approaches.
The following examples highlight current strategies being developed and future areas of focus for adaptation:
Additional Resources on Assessing and Adapting to Climate Impacts