What are climate signals?

Climate signals are long-term trends or changes in the climate system due to human-caused greenhouse gas emissions. The ‘signals’ of human-caused climate change are distinct from the ‘noise’ of natural climate variability as well as other ways, such as aerosol pollution, that human activities can affect the climate.

Climate signals embody changes that are well-established through climate change attribution as well as changes that are widely accepted based on available scientific evidence (e.g. observations, modeling, or basic physics).

Examples of climate signals that are well-established through attribution science include temperature and precipitation extremes, sea level rise, and intensifying storms. Some climate signals are more elusive, however, such as decreased precipitation in the southwestern US or intensifying El Niño events. These and other signals are supported by observations and/or modeling but it can be difficult, due to data limitations or the complexity of the systems involved, for scientists to attribute – with the usual standard for statistical significance – the changes to human-caused greenhouse gas emissions. This does not mean the human fingerprint is absent from a signal under question, or even small. It simply means more evidence is needed to determine the nature and extent of human influence.

How do climate signals help explain climate change impacts in real time?

Climate signals serve as the middle links between greenhouse gas emissions and individual climate events. Climate events are environmental hazards or processes that human-caused greenhouse gas emissions have made more likely, severe, or damaging, such as heat waves, extreme storms or glacial retreat.

Rather than waiting for scientists to conduct a formal attribution analysis for a climate event, the Climate Signals platform links individual events to climate change by demonstrating how an event exemplifies, or is consistent with, long-term trends or changes expected in a warmer world as determined by attribution science as well as observations, modeling, and basic physics.


Greenhouse Gas Emissions

Heat trapping gasses, such as CO2 and methane, drive rising temperatures. Emission of CO2 also drives acidification of oceans.
Long-term trends, model projections, and basic physics link climate change to individual events.
Long-term trends, model projections, and basic physics link climate change to individual events.
Long-term trends, model projections, and basic physics link climate change to individual events.

Climate Signals

Climate Event

Events are shaped by many factors. Increasingly climate change is a factor, particularly when climate change pushes systems past tipping points.

Select a pillar to filter signals

Air Mass Temperature Increase
Arctic Amplification
Extreme Heat and Heat Waves
Glacier and Ice Sheet Melt
Global Warming
Greenhouse Gas Emissions
Land Ice and Snow Cover Decline
Land Surface Temperature Increase
Permafrost Thaw
Precipitation Falls as Rain Instead of Snow
Sea Ice Decline
Sea Surface Temperature Increase
Season Creep/ Phenology Change
Snowpack Decline
Snowpack Melting Earlier and/or Faster
Atmospheric Moisture Increase
Extreme Precipitation Increase
Runoff and Flood Risk Increase
Total Precipitation Increase
Atmospheric Blocking Increase
Atmospheric River Change
Extreme El Niño Frequency Increase
Gulf Stream System Weakening
Hadley Cell Expansion
Large Scale Global Circulation Change/ Dynamical Changes
North Atlantic Surface Temperature Decrease
Ocean Acidification Increase
Southwestern US Precipitation Decrease
Surface Ozone Change
Surface Wind Speed Change
Drought Risk Increase
Land Surface Drying Increase
Intense Atlantic Hurricane Frequency Increase
Intense Cyclone, Hurricane, Typhoon Frequency Increase
Intense Northwest Pacific Typhoon Frequency Increase
Tropical Cyclone Steering Change
Wildfire Risk Increase
Coastal Flooding Increase
Sea Level Rise
Air Mass Temperature Increase
Storm Surge Increase
Thermal Expansion of the Ocean
Winter Storm Risk Increase
Coral Bleaching Increase
Habitat Shift or Decline
Parasite, Bacteria and Virus Population Increase
Pine Beetle Outbreaks
Heat-Related Illness Increase
Infectious Gastrointestinal Disease Risk Increase
Respiratory Disease Risk Increase
Vector-Borne Disease Risk Increase
Storm Intensity Increase
Tornado Risk Increase
Wind Damage Risk Increase
What are Climate Signals?