BIG PICTURE: Global Climate Change

GREENHOUSE GASSES: Drivers of Global Climate Change

We’ve all heard horror stories about kids or dogs left inside cars on a sunny day. The glass in car windows lets short wave sun rays to pass through but holds in the re-radiated longer wave radiation. This same phenomena drives global climate change: high energy short wave solar radiation comes in, and CO2 and other greenhouse gases – just like the car windows – hold in longer wave, re-radiated heat.

Three Global Climate Change Facts

FACT NUMBER 1

Carbon dioxide in the atmosphere is higher than any time in the last 650,000 years, with a dramatic growth spike in in the last 200 years.

FACT NUMBER 2

Temperature and the concentration of climate change gases in the atmosphere are highly correlated. Using small bubbles of air trapped in ancient ice core, researchers have learned that for the last million years, when atmospheric CO2 concentrations grow, the earth gets hotter.

FACT NUMBER 3

Greenhouse (heat trapping) gases are released through human activities such as deforestation and burning fossil fuels, as well as natural processes such as respiration and volcanic eruptions.

What is the difference between climate and weather?
What is driving changes in climate?

Weather is the hour-to-hour, day-to-day state of what is happening in the atmosphere, and including temperature, humidity, precipitation, cloudiness and other factors. Climate is how the atmosphere behaves over long periods of time – it is essentially a set of weather averages for a particular region. Therefore, climate change is a discussion of changes in long-term weather averages.

The earth has seen wide variations in climate over its five billion year history. What is unique about the current situation is the rapidity of change, and the clear linkage between changes and human activities. Carbon and other human-generated greenhouse gases in the atmosphere are widely accepted to be the biggest drivers of current climate change. Other background, but shorter term and less potent factors include volcanic eruptions and semi-regular changes in ocean systems such as Pacific Decadal Oscillation, El Nino and La Nina.

Alaska is Far From Alone in Facing Dramatic Climate Change Impacts

Sea level rise, ocean acidification, harmful algal blooms, shifting habitats, erosion and flooding, invasive species…. Alaska is far from alone in facing dramatic climate change impacts. With rare exceptions, the entire world has shifted from doubting to accepting the realities of climate change. From remote Indian Ocean islands, to the world’s largest cities, to ski areas and insurance companies, people, governments and businesses are now focused on predicting the impacts of climate change, and developing practical response strategies.

ISLAND OF MALE IN THE MALDIVES

The island of Male, capital of the Maldives Islands in the Indian Ocean, is at ground zero in Earth's sea level rise dilemma. With a maximum elevation of only 8 feet above sea level, even a modest increase in ocean heights would submerge a majority of its territory. To combat the threat, the government erected a seawall around the entire island.

PROJECTED FLOOD RISK FOR NEW YORK CITY IN 2050

In New York and cities around the world, sea level rise and storm surges put at risk billions of dollars of infrastructure and millions of lives. The map at right shows areas of New York City as risk of flooding.

GLOBAL RISKS IMPACT ALASKA

The magnitude of risks in major world cities increases the challenges of finding funding and other resources for sparsely populated areas like communities in western Alaska. As one person said: “New York, New Orleans, New Jersey, Newtok?”

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