Would global warming still happen without pollution?

Sandy Marie Bonny
23 January 2012

The consensus is in: Earth is getting hotter! In 1988 the United Nations gathered a group of international scientists and policy makers, the Intergovernmental Panel on Climate Change (IPCC), to explore the possible causes and effects of global warming. In 2007, they concluded that man-made gas emissions are a major driving force behind climate change — contributing to more than 50% of recent global warming via the greenhouse effect.

Did You Know?
Although global warming wasn't recognized until the 1980's, the greenhouse effect was discovered nearly a century earlier in 1896 by chemist Svante Arrhenius — a real forward thinker!

The greenhouse effect is a net warming of Earth's surface by its atmosphere: certain atmospheric gases, greenhouse gases, are able to absorb infrared energy emitted by the Earth, preventing heat from escaping to space. Carbon dioxide, methane, and water vapour, are Earth's main greenhouse gases, acting together to keep Earth's surface ~33°C warmer than it would be otherwise. Without them, Earth would be cold, icy, and inhospitable to the evolution of life as we know it. Today though, greenhouse gases are bringing about global warming and climate changes that are threatening the stability of many ecosystems. This is because their concentrations in the atmosphere are rising at unprecedented levels, partly because of 'air pollution'. Carbon dioxide and methane are released from human combustion of fossil fuels (coal, gas and oil)

Did You Know?
700 million years ago Earth fell into a major ice age where most of the oceans were covered by ice.

What broke us out of that deep-freeze? Volcanoes pumped greenhouse gases into the atmosphere!, causing greenhouse warming of air masses which increase the atmosphere's ability to hold a third greenhouse gas, water vapour. And unfortunately, even if we cut off all sources of air pollution today, greenhouse gas concentrations would likely continue to rise because of other processes. On land, plants remove carbon dioxide from the atmosphere during photosynthesis, converting it into plant sugars and oxygen — so when we clear an acre of rainforest, or pave an acre of grassland, we are reducing the capacity the Earth to remove carbon dioxide from it's atmosphere. Destruction of land plant habitat is a major contributor to global warming. In the oceans, global warming has also increased sea surface temperatures, threatening photosynthetic marine algae, and inhibiting the ocean's ability to 'sponge up' carbon dioxide from the atmosphere.

Did You Know?
Up to half of the carbon dioxide emitted by fossil fuel combustion since 1800 has been absorbed by the oceans!

So, what if we stopped all deforestation, banned concrete, and cooled the ocean with solar-powered fans? Well, there are also thousand and million year cycles of land erosion, ocean-atmosphere carbon exchange, and plate tectonics, all of which interact with carbon dioxide in the atmosphere! The behaviour of these systems is complex and difficult to predict. What we do know is that because greenhouse gas concentrations are affected by more than just how much air pollution we produce, global warming would likely continue for thousands of years even if we stopped or stabilized human greenhouse gas emissions today. But can we slow global warming down? Well, according to the ICPP (2007), the average temperature of Earth's surface could rise by as little as 1.1 to as much as 6.4 °C during the 21st century, depending (among other factors) on how much we reduce our greenhouse gas emissions. So if you're feeling the heat, cut back on your energy consumption, support green energy options, recycling initiatives, and programs that protect natural plant habitats — there is still time to make a difference! References:

ICPP Fourth Assessment Report, 2007. Climate Change 2007, and synthesis report

Tyrrell, T. 2008. Calcium carbonate cycling in future oceans and its influence on future climates. Journal of Plankton Research, 30 (2): 141-156.

Caldeira, K. 2006. Forests, climate, and silicate rock weathering. Journal of Geochemical Exploration, 88 (1-3): 419-422. Lean More:

Calculate your contribution to global warming, and learn how to reduce it!

Support Nature Canada's Forest Protection Petition

Regional effects of global warming and climate change across Canada

Global warming and climate change in the USA

The ocean's ability to take up CO2 — "the Dangers of Ocean Acidification"

Climate Change Myths Debunked by the Sierra Club of Canada

Svante Arrhenius

Sandy Marie Bonny

I am a geobiologist with a doctorate in Earth and Atmospheric Sciences from the University of Alberta. I work as a sessional lecturer, science writer, and creative writer - and yes, the science is almost always stranger than my fiction!


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