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Climate Crisis

This guide provides information, resources, and data on the climate crisis


As greenhouse gas concentrations rise, so does the global surface temperature. The last decade, 2011-2020, is the warmest on record. Since the 1980s, each decade has been warmer than the previous one. Nearly all land areas are seeing more hot days and heat waves.

Higher temperatures increase heat-related illnesses and make working outdoors more difficult. Wildfires start more easily and spread more rapidly when conditions are hotter. Temperatures in the Arctic have warmed at least twice as fast as the global average.

Extreme Cold

There is ongoing debate among scientists about the relationship between climate change and cold spells. While it is clear that climate change is leading to more frequent and intense heat waves (Perkins-Kirkpatrick et al., 2020), the connection between climate change and cold spells is less straightforward.

Some recent research has suggested that climate change may be contributing to more intense and prolonged cold spells in certain regions, due to changes in atmospheric and oceanic circulation patterns. For example, a study published in the Journal of Geophysical Research: Atmosphere (Singh et al., 2016) found that human influence on climate change has increased the likelihood of extreme cold spells in the Eastern part of the United States, while causing warmer winter anomalies in the western states. Another study published in the journal Nature Communications (Cohen et al., 2018) found that climate change may be contributing to increasing the frequency and intensity of cold spells in the United States, but at the same time causing a warming of the  Arctic region.

Matthew Bartow, a climate scientist from UMass Lowell explains that based on research conducted by himself and colleagues, their findings provide  evidence suggesting that Arctic changes associated with global warming have increased the likelihood of such vortex disruptions. The effects of the enhanced high latitude warming known as Arctic amplification on regional snow cover and sea ice may enhance the weather patterns that, in turn, result in a stretched polar vortex.

Severe Storms

Destructive storms have become more intense and more frequent in many regions.

As temperatures rise, more moisture evaporates, which exacerbates extreme rainfall and flooding, causing more destructive storms. The frequency and extent of tropical storms is also affected by the warming ocean.

Cyclones, hurricanes, and typhoons feed on warm waters at the ocean surface. Such storms often destroy homes and communities, causing deaths and huge economic losses.

Experts also say climate change is impacting the conditions in which tornadoes form and could lead to changes in when and where the U.S. sees them. John T. Allen, a professor of meteorology at Central Michigan University, wrote in USA Today opinion column that while ties to climate change are still uncertain, there appears to have been an "eastward shift in tornado frequency" and increasing frequency of tornadoes in outbreaks over the past few decades. Brooks, of NOAA's National Severe Storms Laboratory, said the U.S. is likely to see more tornadoes in the winter (and fewer in the summer) as national temperatures rise above the long-term average.


Climate change is changing water availability, making it scarcer in more regions. Global warming exacerbates water shortages in already water-stressed regions and is leading to an increased risk of agricultural droughts affecting crops, and ecological droughts increasing the vulnerability of ecosystems.

Droughts can also stir destructive sand and dust storms that can move billions of tons of sand across continents. Deserts are expanding, reducing land for growing food. Many people now face the threat of not having enough water on a regular basis.

Flooding/Extreme Rainfall

Floods are already the most common and among the most deadly disasters in the United States. As global warming continues to exacerbate sea level rise and extreme weather, flood-prone areas around the country are expected to grow by nearly half in just this century. 

Many low-lying regions along the coasts of Latin America, Africa, and Southeast Asia may face a severe threat of permanent inundation, part of an alarming trend with the potential to trigger a reversal in human development in coastal communities worldwide. 

  • By 2050, projections show hundreds of highly populated coastal cities will be exposed to increased flood risk, including land home to roughly 5 percent of the population of coastal cities including Santos, Brazil, Cotonou, Benin, and Kolkata, India
  • The impacts on coastal regions, which are often sites for major social and economic hubs, could potentially trigger reversals in human development worldwide.
  • 14 million more people worldwide now live in coastal communities with a 1-in-20 annual chance of flooding
  • Continuing our current course of global greenhouse gas emissions (SSP2-4.5) is projected by the end of the century to expand this 1-in-20 floodplain to areas today populated by nearly 73 million people

Types of Flooding
River Flooding

This occurs when a river or stream overflows its natural banks and inundates normally dry land. ost common in early spring, river flooding can result from heavy rainfall, rapidly melting snow, or ice jams. 

Coastal Flooding

This occurs when winds from a coastal storm, such as a hurricane or nor’easter, push a storm surge (essentially, a wall of water) from the ocean onto land. There are also increasing numbers of shallow, nondeadly floods caused by higher sea levels. These high tide floods (also known as “nuisance” or “sunny day” floods) occur when the sea washes up and over roads and into storm drains as the daily tides roll in. 

Flash Flooding

These quick-rising floods are most often caused by heavy rains over a short period—usually six hours or less. Flash floods can happen anywhere, and low-lying areas with poor drainage are particularly vulnerable. 

Urban Flooding

The term urban flooding refers specifically to flooding that occurs when rainfall—not an overflowing body of water—overwhelms the stormwater drainage capacity of a densely populated area.


Although wildfires are a natural occurrence within some forest ecosystems, fire seasons are becoming more extreme and widespread, even in tropical rainforests where fires are atypical and particularly damaging. Hotter, drier weather caused by climate change and poor land management create conditions favorable for more frequent, larger and higher-intensity wildfires.

From 2001 to 2022, there was a total of 126 Mha tree cover lost from fires globally and 333 Mha from all other drivers of loss. The year with the most tree cover loss due to fires during this period was 2016 with 9.63 Mha lost to fires — 32% of all tree cover loss for that year.

From 2001 to 2022Russia had the highest rate of tree cover loss due to fires with an average of 2.54 Mha lost per year.