Climate change can no longer be considered a problem of the future. It is happening now. Our actions today determine tomorrow’s climate and its consequences.

How do we know climate change is happening?

Every day, scientists record temperatures at thousands of weather stations around the world. Different agencies in the U.S. (NASA and NOAA), the U.K. (the Met Office Hadley Center), and independent research groups (UC Berkeley and University of York) analyze the data and provide a big picture overview of average global temperatures compared to a reference value (temperature anomaly). They have found global temperatures are rising, with the last decade the warmest on record. Scientists also take careful measurements of melting land-based ice in Greenland, Antarctica, and the Arctic; retreating glaciers in the Alps, Himalayas, Andes, Rockies, Africa, and Alaska; declining sea ice in the Arctic Ocean; and rising sea levels—all indicators of climate change.

Temperature graphic

Carbon Dioxide

parts per million

Levels are at their highest in over 800,000 years.

Global Temperature

Since 1880

Nineteen of the warmest years on record have occurred since 2000.

Arctic Sea Ice

per decade

The Arctic ice cap is smaller, thinner than at any time in modern history.

What's causing our climate to change?


The Earth’s climate has always fluctuated because of natural reasons, but today we are giving rise to a period of climate instability that would not be occurring naturally. We are doing this by increasing the amount of greenhouse gases in our atmosphere, primarily by burning fossil fuels. Greenhouse gases like carbon dioxide, methane, and nitrous oxide are a small, but critically important, natural part of our atmosphere. Their heat-trapping property is what insulates Earth from the freezing cold of outer space, making our planet warm enough to live on. But as we continue to add more greenhouse gases to the atmosphere, we trap more heat and increase the Earth’s average temperature—which is disrupting our climate system.

Do scientists agree?

Yes, the vast majority of climate scientists—97 percent—agree that the world is unequivocally warming and that human activity is the primary cause of the warming over the past century. Thousands of studies conducted by researchers around the world have documented climate warming trends, and while spirited debates on some details of climate science continue, these fundamental conclusions are not in dispute. The pace of change is accelerating and the broad-reaching effects of climate change are becoming more apparent. The amount of carbon dioxide (CO2) in the atmosphere now exceeds 410 parts per million. This is the highest it has been in hundreds of thousands of years.

CO2 data

What are the impacts?

data showing sea level rise

Climate change can no longer be considered a problem of the future. It is happening now, and the impacts are being observed all over the world. Examples include:

  • Increased flooding
  • Sea level rise
  • Disappearing glaciers
  • Rise in frequency and range of infectious disease
  • Longer wildfire seasons
  • Loss of biodiversity
  • Stronger hurricanes
  • Damage to coral reefs


Graphics adapted from NASA, NOAA and the U.S. EPA, January 2020

Heat Waves

Record-breaking temperatures and increasing demand for cooling


Changing rainfall patterns and heavier downpours

Stressed Environments

Increasing demand for diminishing physical and biological resources

Science-based, interdisciplinary research and analysis for people and our planet

Decades of research have provided a good understanding of the basic links between human activities, greenhouse gas emissions, changes in the atmosphere, the response of the physical climate system and the impacts on human and natural systems.

More detailed aspects of the problem remain active research areas at Purdue, such as climate sensitivity, impact projections as well as how individuals, cities and the international community are responding to climate change.


Faculty affiliates




Scientific papers


Student affiliates



Understanding Earth’s climate over time

Past climate information gives context to our present climate and future change. Analyzing ice cores, tree rings, deep ocean sediments and more helps scientists better understand physical mechanisms of climate change. Climate reconstruction at Purdue includes:

  • The Miocene through the Pliocene (2 million to 23 million years ago) to better understand the mechanisms for widespread warming
  • Glacial histories in Greenland and Antarctica (11,700 to 2 million years ago) to determine recent periods of ice-free land masses that would improve current models
  • More recent atmospheric histories (from 100 to 100,000 years ago) using ice cores and tree rings to gauge atmospheric greenhouse gas concentrations

Improving projections of climate change impacts

Communities worldwide have seen observable impacts on water resources, agriculture, ecosystems, economies and infrastructure. Clarifying these impacts regionally improves decision-making and strengthens our responses. Examples of key efforts at Purdue include:

  • Climate change patterns’ effect on species composition of plant and soil microbes, water quality, and soil erosion in natural and agricultural systems
  • A framework to estimate climate sensitivity of end-use energy demand and integrate it with existing energy-economy models
  • Dynamic downscaling to gauge climate change’s effect on the frequency and intensity of tornadoes, hail, flash floods and damaging winds

Responding to change

Purdue researchers are studying various ways to adapt to adverse effects of existing climate change while preparing for future impacts. Our work includes understanding beneficial opportunities, such as longer growing seasons and distribution across regions.

Current projects at Purdue aim to:

  • Establish on-farm water storage options to stem water and nutrient loss amid changing climates
  • Explore how cultural and social norms shape individual or group behavior about climate change
  • Develop storm-surge flooding decision support tools for coastal-community policy-makers to evaluate tradeoffs and allocate funding for mitigation
  • Understand heat-stress tolerance at the physiological and genetic levels to create superior plant hybrids that thrive under elevated temperatures

What Can I Do About Climate Change?

Lasting climate solutions will require action on a global scale, but there are many ways that individuals can help pave the way for bigger change. We’ve summarized four practical tips for how YOU can address climate change into a printable poster (right). You can also download each individual "tip card."