Frequently Asked Questions About Climate Change
Climate change is a complicated issue, and there are many resources that can help you understand its twists and turns. To get you started, here are some answers to a few common questions.
Q. What's the difference between weather and climate?
A. The short answer is this: weather is what happens in the atmosphere in one spot over a short period of time. Climate is the average weather pattern over a long period of time. For example, it might sometimes rain in the desert, but the overall climate of the desert is dry.
For a longer answer, read this explanation at NASA's web site.
Q. Is it "climate change" or "global warming"?
A. Think of them as different terms for the same thing, like "creemees" and "soft serve". "Global warming" was the popular term for a while, but some people pointed out that the problem is more complicated than just warming - for example, the average global temperature has increased, but some areas have cooled. "Climate change" may be more accurate, but other people have argued that this might make the problem seem less serious. Which term do you prefer?
For more, read this response at the FAQ page for the University Corporation for Atmospheric Research.
Q. What is climate change, anyway?
A. Climate change is a long-term shift in the elements that make up the climate system, like temperature and wind. The climate has changed in the past, but today's climate change is partly influenced by human activities. How are humans contributing to recent climate change?
It all starts with sunlight. Not all of the light from the sun that reaches Earth warms up the planet's surface -- some bounces off clouds, some is absorbed by the atmosphere, and some is reflected back into the sky (ice, for example, is very reflective!). The planet's surface absorbs about half of the sunlight, and it heats up.
We all know that hot things heat up whatever they're touching -- a hot tea kettle would burn you if you touched it, and even the warm air around it would heat your hand. But all hot things also release a special kind of radiation called longwave radiation. Just like a hot tea kettle, the planet emits this special radiation, and it radiates up into the sky. In the atmosphere, greenhouse gases absorb some of this radiation and release it back to the planet, heating it up. Without this protective "blanket" of greenhouse gases, the planet would be very cold! However, if we have too thick a gas blanket, it gets too hot. Human activities, like driving vehicles, can release these gases and make our planet's blanket warmer.
For a longer explanation of the climate system, read What Factors Determine Earth's Climate? in the IPCC FAQ.
Q. The climate has changed before. Why should we worry about today's changes?
A. The climate has changed many times in the past. However, human civilization developed and thrived during a time when the climate was pretty stable. Today's climate change is unusual because it's warming very quickly. If the climate changes too quickly, lots of plants, animals and human systems (like agriculture) will have trouble keeping up. This period is also unusual because the concentration of C02 in the atmosphere is higher than in the past half-million years, and global temperatures are warmer than they've been in the past 500 years - and probably longer.
So, you'd be correct in saying that our climate has changed in the past. But if the planet started progressing rapidly toward the climates of those time periods (with glaciers, perhaps, or a steamy tropical climate), would our civilization survive? Would you miss any parts of today's climate?
There's a good, quick answer to this question at Grist.org. Also, read this article about climate and civilization at the San Diego Union-Tribune.
Q. Is today's climate change our fault?
A. Scientists from the Intergovernmental Panel on Climate Change say that warming is happening, and that it's "very likely" - 90% likely - that this warming has a human cause. To put this into perspective, imagine a bag with nine black jellybeans and one red jellybean. Imagine that you don't like black jellybeans. Reach into the bag - do you feel confident that you'll choose the red jellybean?
The actual influences of humans on the climate system are complicated. We humans don't just spend our time pumping greenhouse gases into the air -- we engage in all sorts of activities that have different climate impacts. For example, soot from our factories has made our ice and snow more "dirty", so it reflects less sunlight than shiny white snow. A few of our influences have even had a cooling effect on the system. Scientists calculated the overall effect of all the changes we've made since industrialization in the late 1700s, and compared it with natural changes like the sun's energy cycles. They found that human activities have by far exerted the greatest impact on our climate since indistrialization.
You can see a chart of human and natural causes on this page, part of the IPCC's FAQ. You can read about the panel here.
Q. If climate change is real, why was last winter so cold?
A. Weather is always variable, especially in New England! There have always been warmer and cooler winters, and climate change is taking place on top of, and interacting with, all the natural variability. Remember, climate is a long-term average. For example, 2008 felt a lot cooler compared to recent years, but it was still one of the warmest years on record, globally.
Q. Why don't we know exactly what will happen in Burlington?
A. Some parts of climate change (like rainfall changes) are very complex, and it's difficult to make a perfect projection for a place as small and specific as Burlington. Also, nobody knows how much CO2 we will release into the atmosphere in the next few decades. Scientists are tackling this uncertainty by carefully building complex models to give us several of possible future changes depending on how much CO2 we might produce. They are also studying climate at the global level and at the regional level.
Q. If we don't know exactly what will happen, why should we try to stop it?
A. We don't know when the next big earthquake along the West Coast will happen, but we know that it will happen, so we should still build earthquake-resistant buildings. Similarly, we know that the climate will warm, and we can project future warming within a certain temperature range. Fortunately, scientists believe that we can avoid the worst changes by taking action now.
This answer is a simple version of a reply at Union of Concerned Scientists web site. Explore the site for many more questions and answers.
Q. If we stopped releasing greenhouse gases today, would climate change stop?
A. Climate change is like a big wheel that we've set in motion: even if we leave it alone, the wheel will keep turning for a while. Temperatures will rise a bit more, and some effects will linger for a long time.
A press release by the US National Oceanic and Atmospheric Administration talks about research into long-term changes.
Q. If there's nothing we can do to reverse climate change, should we give up?
A. No, we shouldn't! The CO2 we've already pumped into the atmosphere will change the climate for a long time to come. However, this change is small compared to the change that scientists project if we don't reduce our greenhouse gas emissions over the next few decades. If we work together, we can slow things down.
The blog RealClimate.org explains why irreversible change doesn't mean unstoppable change.
Q. What does the ozone hole have to do with climate change?
It's easy to confuse the ozone layer problem with the recent climate change problem. In both cases, human activities cause gases to enter the atmosphere, changing its chemistry in a way that can harm life on Earth. However, these problems are quite different. It's best to understand them as separate issues that have several connections.
The ozone layer and climate change have a complex relationship: some of the effects of greenhouse gases are slowing the ozone layer's recovery, and some are speeding it up. The thinning ozone layer also affects climate; for example, ozone absorbs sunlight and heats up, so its loss over the Antarctic is helping to cool parts of the continent.
There's another important connection. The 1987 agreement to protect the ozone layer marked an incredible international effort to protect our atmosphere. We've come together on atmospheric issues before - we can do it again.
To explore the connections between ozone and climate, visit this reply at the Union of Concerned Scientists site.
Q. I'm doing just fine! Why should I worry about trees and flowers?
Remember, climate change isn't just about green things. It's about human health, agriculture, financial security and political stability. It's also about the seasons we love and the seasonal activities we enjoy.
Check out the New York Times article "Climate Change Seen as Threat to U.S. Security".
I still don't think I understand.
That's okay! You should read everything you can about climate change and develop your own informed opinions about what you should do. An issue this important and complex needs some time and attenion, but there are many resources that will help you become a climate expert.
One place to start is RealClimate.org's starting page.
