This year is already on pace to be the hottest year in human history.
No supercomputer model has accurately predicted the rapid pace at which our planet is warming. Many climate scientists are bewildered as global temperatures rise faster than expected and extreme weather events wreak havoc on communities around the world.
What are these climate models missing? The Michigan State University College of Natural Science recently discussed this question with climate researcher Wolfgang Bauer, a University Distinguished Professor in the physics and astronomy department. Here, Bauer explains an important detail that climate models aren’t taking into account — and what, if anything, we can do to make our environment more resilient.
We’ve talked about global warming and climate change for decades. Where do you think our planet stands? Are we at a tipping point?
I feel like holding up a sign that says, “The end is near” and standing out in Times Square. I do think climate change can be reversed but, right now, it’s rapidly getting worse.
For the last three years, each year was the warmest in the history of humankind. And what’s even more troubling is that all large supercomputer-based climate models under-predicted the warming.
The other thing that’s worrisome to me is our reliance on climate models that haven’t delivered more precise predictions since the 1970s. The first model that made these predictions in 1979 was created by the world’s most powerful supercomputer at the time. It predicted some degree of warming with a potential error bar of something like 5 degrees.
Now, fast forward 45 years later. Computers have gotten more powerful by a factor of more than a billion. You’d think these computers should deliver smaller uncertainties. It turns out, error bars have not shrunk but have become slightly bigger. Our predictions are not getting more certain, but slightly more uncertain.
Why are our current climate models so inaccurate?
We understand what our atmosphere does fairly well. As you inject all these many billions of tons of carbon dioxide and other greenhouse gasses into the atmosphere each year, its absorption increases. That means it makes a thicker and thicker blanket that prevents heat from escaping around us.
What’s not quite as well understood is the other side of that equation. There’s a term that often gets swept under the rug in global warming discussions and that is reflectivity, or how much of the sun’s radiation is reflected away. As the sun delivers heat, the Earth must either reflect this heat or raise its own temperature to radiate that heat away. This needs to be in equilibrium.
The really bad news is we don’t quite understand all the minute details of this reflectivity. We need to understand that precisely, to something like 0.001%, and that is hard. There are satellites set up with detectors that measure the light that gets reflected, which is mainly visible light. They also measure the infrared light that’s radiated from the Earth.
We know from these measurements that snow has a reflectivity rate of about 70%. For grass, that’s about 30%. Asphalt, however, reflects 10% of light. So, every time you replace a grass patch with a parking lot, you have ever so slightly reduced the reflectivity of Earth.
The entire built environment — roads, railroad tracks, parking lots, houses, factories, everything we have constructed as humans — is about 1% of the entire surface area of the Earth. Those black roof shingles we have on our houses absorb heat. There’s very little reflection from streets and parking lots. Because the Earth’s temperature is rising, we have less snow cover, so there’s less light reflecting off the Earth each year. There is an exponential increase in temperature that is possible if we don’t stop this reduction in snow cover.
Is there a better way to predict how the Earth’s temperature will increase?
If we incorporate the reflectivity feedback loop into the existing climate data, it’s a much better description than the linear increase most supercomputer models predict. I input the incoming solar radiation, minus the reflected part. If I allow this reflectivity to very gradually but exponentially decrease, I can describe the temperature of the Earth perfectly, just from my laptop. What that predicts is that the year 2025 will again be the hottest in history, and it will again overshoot everything that the supercomputer global climate models predict until they get around to a more accurate representation of Earth’s reflectivity.
Can we do anything to reverse climate change? Or is it too late?
We need to look at our built environment and look for simple alternatives. We can make changes as basic as using concrete instead of asphalt, and making concrete that’s more reflective. Using a material other than black asphalt roof shingles would make a difference. Separately, these are small changes, but all of them together could help.
For example, there’s a 100-square-mile community in the southern tip of Spain that is covered in white tarps. These tarps are for greenhouses and agricultural production. It’s like a sea of plastic that you can literally see from space. When a local university studied the temperature in that area relative to the surrounding land mass, they found that the community was roughly 3 degrees cooler. That is very significant.
Now, I don’t advocate for covering everything in white tarps. That has its own problems. But even some white paint would do a lot of good.
Of course, the main thing is we still need to stop burning fossil fuels. That’s the most essential part that we cannot neglect. The really great news, though, is green power from solar, wind and hydropower is now cheaper than generating power from burning fossil fuels. By making the switch to renewables, we not only have the chance to save our planet, but we can also become more prosperous in the process. Win-win! What better message can there be on Earth Day?