Climate Evidence: Is the climate warming?

The first question we have to ask : is the climate warming? What is the evidence? And is it changing enough to make a difference?

Study Guide: use the following questions to help you focus on the important parts of the material

2. Is the climate warming?

• • What is the current average temperature for the earth?
  • How much warmer is that than historical averages?
  • Compare the rate of change in the last 100 years compared to the rate of change in the past.
  • Why do a few degrees matter?

Global Temperatures

Our current global temperature is on average (as of April 20th, 2021 when I checked NASA's website Links to an external site.)

+0.85 ^o Celsius warmer than in the 1880's

To put that in perspective, average global temperatures don't fluctuate that widely. Look at the graph below and you can see that over the course of human history (last 10,000 years or so), we haven't seen this big a change.

In the animation in the above video, the Earth rides the "Global Temperature Anomaly," a rollercoaster that shows the difference from historic average temperature since the last ice age.  

Not only is the current “hill” on the roller coaster as high or higher than anything our species has experienced since we first settled down from a hunter-gatherer lifestyle, but it’s also the steepest climb. Compared to the past 11,000 years, the current track is nearly vertical.

This climate model simulation was made for the United Nations' Intergovernmental Panel on Climate Change Fourth Assessment Report, showing five-year averaged surface air temperature anomalies in degrees Celsius from 1880 to 2100.

See accessible description of the Surface Air Temperature animated video Download See accessible description of the Surface Air Temperature animated video

And this graph over the last 2000 years.

Text description of Global warming / cooling rates over the past 2,000 years (Word doc) Download Text description of Global warming / cooling rates over the past 2,000 years (Word doc)

What Do a Few Degrees Matter?

A common question is whether the amount of global warming actually makes a difference.

Evidence for Global Warming

NASA has put together a great set of resources to examine the types of evidence showing that the earth's temperature has been rising dramatically.

• • Read NASA's Climate Change, How Do We Know Links to an external site.? and use it to answer the questions in the study guide questions above.
  • Then take the mini quiz on the next page.