Climate change is having an ever greater impact on our lives, not just through extreme weather disasters but also in slowly creeping temperatures and wildly variable weather patterns that hurt agriculture, human health, infrastructure, livelihoods and economies. Journalists should be drawing those connections to help the public understand what’s at stake.
Whenever extreme weather occurs people often ask, “Did climate change cause that?” Scientists will say that’s the wrong question. The way to think about it is, “Did climate change make it worse?” In many cases, climate science is already answering that question. When there’s not a specific source or study handy, these facts, compiled by NPR’s climate editors, can provide big-picture context for weather events and other stories.
Many are drawn from the latest National Climate Assessment, the gold standard for U.S. climate data until the next such report in 2022. If you want to go deeper, there are chapters by topic and region. And the first and last sentences of the report’s overview are a succinct snapshot of where things stand:
Earth’s climate is now changing faster than at any point in the history of modern civilization, primarily as a result of human activities … While Americans are responding in ways that can bolster resilience and improve livelihoods, neither global efforts to mitigate the causes of climate change nor regional efforts to adapt to the impacts currently approach the scales needed to avoid substantial damages to the U.S. economy, environment, and human health and well-being over the coming decades.
How much has the climate warmed?
- The average global temperature has already increased about 2 degrees Fahrenheit (a little more than 1 degree Celsius) compared to pre-industrial times.
- Global warming is accelerating. It is caused by human greenhouse gas emissions.
- Scientists say humans must limit global warming to 1.5 degrees Celsius above pre-industrial levels to avoid the most catastrophic effects of climate change. We are not on track to achieve that goal under current policies. Parts of the U.S, and the world, already have average temperatures that exceed 2 degrees Celsius above pre-industrial levels.
How is warming affecting the weather and other things?
- The warming climate is making heat waves, droughts and floods more frequent and intense.
- Winters are warming faster than other seasons. That’s melting snowpack earlier, hurting crops that need freezing temperatures and expanding the range of vector-borne diseases.
Flooding and sea level rise
- Floods are getting more frequent and severe in most of the U.S. because of more extreme precipitation and sea level rise from climate change.
- In the U.S., sea levels are rising fastest on the East and Gulf coasts, with many communities disrupted by flooding even on sunny days.
- Scientists warn that, without dramatic cuts in carbon emissions, rising sea levels will displace millions later this century.
- Hurricanes are causing more severe floods because of the combined effects of higher seas, warmer air and warmer ocean water.
- Hurricanes are moving more slowly and dropping more rain as the Earth gets hotter. Once they make landfall, they still pack a big punch and lose their power much more slowly. Fifty years ago, a typical storm would lose 75% of its strength within the first 24 hours after it came on land. Now, it loses only 50% in the same time period.
- Hurricanes are more likely to be larger and more powerful when they form over hotter ocean water. Climate change is causing global sea surface temperatures to rise.
- Climate change makes large, destructive wildfires more likely because of hotter temperatures and drier vegetation. Other factors include expanding development, and an overabundance of fuel because of past fire suppression.
- Higher average temperatures are increasing the length of fire season and the number of places where fires can occur. In recent years, fires have expanded in the Arctic and even in some rainforests.
Biodiversity and habitat
- Human activities, including climate change, have put roughly a million species at risk of extinction, many within decades. Climate change is expected to become the leading cause of extinction as temperatures warm.
- Warmer temperatures and altered precipitation patterns upset the stability of natural ecosystems, threatening biodiversity.
- Scientists say the warming climate endangers Americans’ health through extreme weather disasters, deadly heat, unhealthy air and more diseases.
- The warming climate already is making it harder to grow food in some parts of the world, like California, which depends on snow piling up in the Sierra Nevada mountains for irrigation. Climate models predict more serious disruption to global agriculture a few decades in the future because of shifting rainfall and extreme weather.
- About a quarter of all global greenhouse gas emissions come from growing food. Land clearing is the biggest single reason, because it releases carbon dioxide stored in the soil and trees. Other greenhouse emissions come from nitrogen fertilizer and — famously — the methane-laden burps of cattle and sheep.
- There are potential solutions for reducing greenhouse emissions from agriculture. The most important change would be to use less land to grow food, converting cropland to permanent grassland or forests that can capture carbon dioxide from the air. This could be done by increasing productivity on existing land, eating less meat (especially beef) and reducing the use of biofuels like ethanol, which is made from corn.
How much time do we have to end carbon emissions?
- Scientists say the world needs to essentially eliminate new carbon emissions by 2050 to avoid the most catastrophic impacts of climate change. Because that is such a daunting challenge, they say new technologies are needed to actually remove greenhouse gases from the atmosphere.
- Carbon dioxide emissions stay in the atmosphere for hundreds of years, so even if they fell to zero the planet would continue warming for a long time. But cutting emissions now means that humans will avoid even worse disasters than the ones we’re already coping with.