It is the extremes in weather that get our attention. California is undergoing one of the worst droughts in 500 years. England was under water after the wettest winter on record. And Australia’s heatwaves continue to break records of their own.

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Even at levels of warming well below two degrees Celsius (the level agreed by scientists to be the maximum ‘safe’ increase in average temperatures this century) these events are getting people’s attention. And for good reason – extremes in weather and climate affect every sector of the global economy.

The worst can threaten biodiversity, upset food production, overwhelm infrastructure, destroy homes, and can set back or cripple the economy. But the direct impact to humans can be just as extreme, destroying livelihoods, creating refugees and often causing further stresses to already politically unstable regions. 

The Earth’s climate is always changing, but it’s the speed and the amount of change that can be an issue. As people like Tim Flannery, Al Gore, Jim Hansen, James Lovelock and Crispin Tickell have eloquently explained, for the last 800,000 years, the Earth’s temperature has fluctuated within a relatively consistent and narrow range, and ecosystems have evolved to thrive in that range.

Though there have been occasional extremes in the past, climate change is now throwing us into a whole new weather regime. Nine of the 10 hottest years ever recorded have occurred since 2000, hurricanes are becoming stronger and more intense, and the Fifth Assessment Report by the Intergovernmental Panel on Climate Change concludes that it is “extremely likely” (95-100% certainty) that human activities have been the main contributor to climate change in recent years. 

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If we carry on as we do at the moment, the World Bank estimates that the Earth will warm by approximately four degrees Celsius (nine degrees Fahrenheit), within in the next 100 years. Four degrees might not sound too unpleasant where you live, but average change for the whole planet means that some places might get dozens of degrees hotter.

And as Prof. Hansen has pointed out, that amount of temperature rise for the Earth means the whole planet is gaining the equivalent of 400,000 Hiroshima bombs of energy every day.

That massive energy imbalance isn’t going unnoticed by the climate. In 2012, 362 sites in the United States experienced all-time record high temperatures, while zero sites recorded all-time low temperatures. In the first month of 2014, Australia experienced unprecedented high temperatures, with inland regions of the country reaching up to 50°C. 

Western Europe’s heatwave during the summer of 2013 brought monthly temperatures up to 2.2°C above the average for that region, and meteorologists are already speculating that Europe’s summer in 2014 could be another scorcher. 

In the same way that temperature patterns are shifting, so too are average levels of rainfall around the world.

While some regions are experiencing increasingly frequent and intense drought conditions, other parts of the world are getting bombarded by more rain and snow. And one need not travel far to experience both of these extreme weather phenomena. In January 2014, nearly 95% of California was under drought conditions, and cities like San Francisco and Santa Barbara were experiencing record Celsius temperature highs in the mid-20s. Meanwhile, the United States’ Midwest and east coast were experiencing extreme snow, with a year’s worth falling in Chicago and Detroit in a single month.

As history and experience have shown, the damages from isolated extreme weather events can be massive, and these phenomena do occur even without changes in the background state of the climate system.

But as the Earth’s temperature continues to rise we will begin to experience these kinds of events more often. In combination, these weather events present immense economic, social, and political risk. 2011 was the costliest year for natural disasters, reaching a record-breaking $380 billion, though this record will likely be beaten in the near future as the globe experiences even more extreme weather events.

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We have the potential to lessen the impact of these extremes by cutting emissions now. If we aggressively deploy emissions-reduction technologies today, we still have a chance of slowing the effects of climate change and limiting the global average temperature increase.

Countless renewable energy technologies exist and have reached commercial scale including solar, wind and hydropower. Ways of renewably storing and using that energy, from sustainable jet fuels to better electric batteries are continuing to move forward. People are working to protect and restore the ecosystems of the world, and more and more people are being educated and informed on the problems the world is facing.

But this alone is not enough. We need to couple clean innovation with sound policy to integrate these new technologies into our future blueprint for a prosperous society. And we need these policies to work and move internationally as effectively as greenhouse gases move around the atmosphere.

Starting now – and starting fast – is the best way to reduce the impacts of climate change and put us on the path to a prosperous future with a stable climate system and healthy oceans.

Success is possible, but it isn’t guaranteed. And in the next few years the world will decide which path it’s going to take. 

-This is a guest blog by Hal Harvey and Hallie Kennan from Energy Innovation 

Image courtesy of Flickr/iglooo101