Global Warming

Floods. Droughts. Heat waves. Monster wildfires. Climate change is not just about polar bears, the iconic symbol of a melting Arctic. Global warming affects the entire planet.

In fact, if our chief scientist, Dr. Steven C. Amstrup, had his way, every news report on the latest weather disaster would end with these words:

"Events like these will continue to increase in number and severity as the world continues to warm."

What's causing global warming?
Do scientists agree about global warming?
How are polar bears affected by global warming?
What can be done?
When will my actions make a difference?

What's causing global warming?

Greenhouse gases (GHGs) in the atmosphere act like a blanket that keeps the Earth warm. This protective blanket helps make our planet habitable. But over the past 200 years, humans have greatly increased the level of GHGs in the atmosphere by burning fossil fuels like oil and coal. This is like throwing on a second blanket, causing temperatures to rise.

Other factors such as deforestation have added to the problem. Trees soak up carbon dioxide, one of the greenhouse gases, from the air. Fewer trees, especially in the tropics, means less CO2 is removed from the atmosphere.

Do scientists agree about global warming?

The laws of physics dictate that the world will grow warmer and warmer as greenhouse gas concentrations rise. There's no uncertainty about this: scientists have understood the correlation for over a hundred years. Venus is a perfect example of a planet swaddled thickly in greenhouse gases and too hot.

Are scientists still debating global warming? No. Over 97% of climate scientists—the experts in their field—agree that human activities are causing the current warming and related climate chaos.

The important point to remember is that natural fluctuations in the climate system will continue with global warming, but the baseline will climb higher and higher. This means that scientists can't confidently predict, for example, the first year it will be too hot to grow wheat in Kansas or the first summer the Arctic will be ice-free. But crossing both thresholds is assured unless we reduce greenhouse gas emissions.

And once we cross those thresholds, it will be bad news not only for polar bears—but countless other species, including humans.

How are polar bears affected by global warming?

Polar bears have evolved for a life on the sea ice, which they rely on for reaching their seal prey. But the arctic sea ice is rapidly diminishing due to a warming Earth, affecting the entire arctic ecosystem, from copepods to seals to walruses. For polar bears, sea ice losses mean:

  • Reduced access to food
  • Drop in body condition
  • Lower cub survival rates
  • Increase in drowning
  • Increase in cannibalism
  • Loss of access to denning areas
  • *Declining population size

What can be done?

If greenhouse gas levels continue to rise, polar bears and many other species will perish. But because humans are causing this problem, humans can fix it. Scientists say that time remains to save polar bears if we act soon to greatly reduce greenhouse gas emissions. This means all of us—individuals, communities, businesses, and governments—must work together now. Join us in playing a role to save polar bears.

When will my actions make a difference?

Taking action now won't result in an immediate stop to global warming. It will take decades to reduce the build-up of greenhouse gases already blanketing the atmosphere. But your actions today will help prevent catastrophic changes from taking place—not only saving polar bears, but life as we know it on Earth.

For more on climate change, visit RealClimate and Skeptical Science.

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