showing 15 of 15 learning pages IN: Climate
The climate is the long-term weather pattern in an area, usually measured over a period of 30 years. The Earth’s climate system includes the atmosphere (the air that surrounds the earth), hydrosphere (oceans, rivers, lakes, streams and groundwater), cryosphere (ice sheets, glaciers, sea ice), lithosphere (land surfaces, rocks) and biosphere (living things), and the ways they all interact.
The Earth’s climate has warmed and cooled many times over millions of years. Most of these changes took place over many thousands of years in response to natural processes. Past changes in the global climate can be explained by a range of factors, which scientists call ‘forcings’.
The Earth’s climate, which has been stable throughout most of human history, is now changing rapidly. The polar regions are heating up more quickly than the rest of the planet, and the Antarctic Peninsula is one of the fastest-warming places on earth. Antarctica is changing in ways that will impact all of humanity. Ice shelves in Antarctica may be approaching tipping points, which could lead to several feet of sea level rise by 2100. The Southern Ocean is becoming warmer and more acidic, threatening delicately balanced Antarctic ecosystems. Penguin colonies are declining, even disappearing from colonies they have inhabited for decades or more.
The Antarctic Ice Sheet covers an area larger than the United States and Mexico combined. Its white surface acts as an enormous reflector, sending heat back to space and keeping the planet cool. The Antarctic Ice Sheet is losing ice. Net ice loss from the Antarctic Ice Sheet is currently 100-200 billion tons per year, and has increased in the past two decades. The rate of loss is continuing to increase, with sea levels rising faster each year.
Antarctica’s ice shelves are shrinking. Every year for the past 25 years, Antarctic ice shelves have been losing mass. Many of them are becoming thinner, smaller and more vulnerable to sudden collapse on a large scale, with impacts that affect all of humanity.
Sea ice is a crucial component of our planet’s climate system, and one that is highly vulnerable to climate change and variability. Antarctic sea ice is also a critical habitat for marine life, including penguins and seals. Antarctic sea ice is changing, with impacts on Antarctic penguins and important global ocean currents.
The planet is heating up. Over the past 50 years, the ocean has absorbed over 90 percent of the excess heat produced by human activity. Most of this has taken place in the Southern Ocean, where a unique network of currents connecting surface waters with the deep ocean take extra heat from the surface to the depths, where it can be stored for centuries.
Ocean currents play a vital role in regulating the earth’s climate by moving water, heat, carbon and nutrients from one part of the ocean to another. Cold, salty water produced around Antarctica drives the deep, slow-moving currents that help regulate the earth’s climate. Around Antarctica, the composition of the ocean is changing. In some areas it is becoming warmer, fresher and less dense. As Antarctic water becomes lighter its pumping action could become less powerful, leading to disruptive changes in global ocean circulation.
The ocean absorbs almost half of the carbon dioxide released into the atmosphere by human activity. Although the Southern Ocean only makes up 10-15% of the global ocean, it absorbs almost half of all the carbon dioxide taken in by the ocean. If we continue on our current emissions trajectory, by 2300 the ocean will be more acidic than it has been in around 20 million years, and the rate of change could be faster than any time in history. We are entering uncharted territory, racing towards an ocean with a chemical composition we have never seen before.
Almost all Antarctic life begins and ends in the Southern Ocean. As the global climate changes, the Southern Ocean is becoming warmer and more acidic, which is having impacts on many Antarctic species. On the West Antarctic Peninsula, this is happening faster than almost any other place on earth. Scientists report that Antarctic krill swarms and some penguin species appear to be migrating southward to cooler waters. Some colonies of ‘true’ Antarctic species, such as Adélie penguins, have disappeared, while species adapted to warmer conditions flourish.
Sea ice is more than just frozen ocean. Below the surface it is a vibrant ocean oasis, and a vital habitat for life in Antarctica. Billions of microscopic sea plants live underneath the ice, providing food for Antarctic krill and other small crustaceans, which form the foundation of the Antarctic food chain. The sea ice surface is also a critical breeding ground for emperor penguins. In some parts of Antarctica, winter sea ice cover is declining dramatically. Reduced sea ice cover has a domino effect, impacting Antarctic ecosystems from tiny plants to penguins, seals and whales.
Antarctica is a polar desert: around 99% of the continent is permanently covered in ice. Small ice-free areas are home to extremely rare, uniquely-adapted species found nowhere else on the planet. For those hardy species that have managed to gain a foothold on the ice-free land, life is a constant balancing act as they seek out enough food, shelter and water to survive. The climate crisis is threatening the delicate balance that allows these terrestrial ecosystems to survive.
For many years, the majority of Antarctic science took place on national Antarctic expeditions, whose primary objective was not science but exploration. Today, most Antarctic science takes place on national Antarctic research bases, or stations, which are scattered across the Antarctic continent. There are around 80 scientific bases across Antarctica, operated by around 30 different countries. Scientists of all nationalities collaborate, sharing resources and data to achieve the best possible research outcomes for all nations.
The exact origins of modern Antarctic tourism remain hazy. Around the 1950s, Argentine and Chilean operators started offering dedicated tourist voyages with approximately 100 passengers each. The modus operandi was very similar to that in use today. The first Antarctic flights were offered around the same time, with small groups flying from Chile to Antarctica in 1959, although they did not land. Between them, they took around 500 tourists to Antarctica each season.
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