equator

La Niña has arrived

February 26, 2025 By EarthWise Leave a Comment

After seven months of waiting following the end of the recent El Niño condition, La Niña finally showed up in the eastern Pacific Ocean in early December.

El Niño and La Niña are climate patterns in the Pacific Ocean that can affect weather worldwide. Normally, trade winds in the Pacific blow west along the equator, taking warm water from South America towards Asia. To replace the warm water, cold water rises from the depths. During El Niño, trade winds weaken and warm water is pushed back east, toward the west coast of the Americas. As a result, areas in the northern U.S. and Canada are dryer and warmer than usual.

During La Niña, trade winds are stronger than usual, pushing more warm water toward Asia. This results in more upwelling of cooler water from the depths. This tends to lead to drought in the southern U.S. and heavy rains and flooding in the Pacific Northwest and Canada. During a La Niña year, winter temperatures are warmer than normal in the South and cooler than normal in the North.

According to the report published in January by NOAA, the La Niña that has arrived is not a particularly strong one. Sea surface temperatures are only about 1.3 degrees Fahrenheit below average in the tropical Pacific. The report also suggests that the La Niña condition may not stick around very long.

The El Niño-Southern Oscillation phenomenon adds a natural source of year-to-year variability in global temperatures. The presence of La Niña for at least part of this year may temporarily keep the lid on rapidly climbing global temperatures.

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La Niña Is Here

Photo, posted November 23, 2011, courtesy of NASA Goddard Space Flight Center via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Shrinking African glaciers

March 27, 2024 By EarthWise Leave a Comment

We don’t usually associate Africa with glaciers, but the continent has had glaciers on its highest peaks for the past 10,000 to 15,000 years. Africa’s glaciers are found in three regions: the Rwenzori Mountains along the border between Uganda and the Democratic Republic of the Congo, Mount Kilimanjaro, and Mount Kenya. At the turn of the 20th century, there were 43 glaciers scattered across 6 peaks within the Rwenzori Mountains. In the intervening years, things have greatly changed.

Since the early 20th century, Africa’s glaciers have shrunk by 90%. Because all these glaciers are close to the equator, they are especially vulnerable to warming. According to a new study published in the journal Environmental Research: Climate, in the last two decades, Africa’s glaciers have lost roughly half their area.

This rapid decrease is alarming to climate scientists because they represent a clear indicator of the impact of climate change. A major factor in the decline of the glaciers is the reduction in cloud cover over the mountains. Sunshine is melting glaciers and turning ice directly into water vapor even when temperatures are below freezing. Reductions in snowfall at the same time means that the melting glaciers are not being replenished.

Scientists believe that the tropical glaciers of Africa may all but disappear over the next 25 years.

Roughly three-quarters of the Earth’s freshwater is stored in the world’s more than 200,000 glaciers. According to scientists, if the world reaches but maintains 1.5 degrees of warming, half of the world’s glaciers could be gone by the end of this century. If the world continues to warm as it has been without slowing down, more than 80% of the glaciers will disappear.

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Africa’s Tropical Glaciers Have Shrunk by 90 Percent, Research Shows

Photo, posted February 26, 2022, courtesy of Ray in Manila via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Disappearing Glaciers | Earth Wise

February 20, 2023 By EarthWise Leave a Comment

Glaciers are massive bodies of slowly moving ice. Glaciers form on land, and represent the snows of centuries compressed over time. They move slowly downward under the influence of their own weight and gravity.

Most of the glaciers on the planet are found in the polar regions, including Antarctica, the Canadian Arctic, and Greenland. Glaciers can also be found closer to the equator in mountain ranges, such as the Andes Mountain range in South America. Glaciers are always changing, accumulating snow in the winter and losing ice to melting in the summer. But in recent times, the melting has been outpacing the accumulation.

A new international study led by researchers at Carnegie Mellon University’s College of Engineering has produced new projections of glacier loss through the century under different emissions scenarios. According to the projections, the world could lose as much as 41% of its total glacier mass this century – or as little as 26% – depending on climate change mitigation efforts.

In a future with continued investments in fossil fuels (sometimes referred to as the “business as usual” scenario), more than 40% of the glacial mass will be gone by 2100, and more than 80% of glaciers by number could disappear. Even in a best case scenario where the increase in global mean temperature is limited to 1.5° degrees Celsius relative to pre-industrial levels, more than 25% of glacial mass will be gone, and nearly 50% of glaciers by number will disappear.

Glaciers take a long time to respond to changes in climate. A complete halt to emissions today would take anywhere from 30 to 100 years to be reflected in glacier mass loss rates.

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Team projects two out of three glaciers could be lost by 2100

Ice, Snow, and Glaciers and the Water Cycle

Photo, posted August 13, 2010, courtesy of Kimberly Vardeman via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Triple La Niña | Earth Wise

January 16, 2023 By EarthWise Leave a Comment

La Niña is an oceanic phenomenon consisting of cooler than normal sea-surface temperatures in the central and eastern tropic Pacific. It is essentially the opposite of the better-known El Niño. These sea-surface phenomena affect weather across the globe. As one oceanographer put it: when the Pacific speaks, the whole world listens.

There is currently a La Niña underway, and it is the third consecutive northern hemisphere winter that has had one. This so-called triple-dip event is rather rare. The only other times they have been recorded over the past 70 years were in 1954-56, 1973-76, and 1998-2001.

La Niñas appear when strong easterly trade winds increase the upwelling of cooler water from the depths of the eastern tropical Pacific Ocean near the equator. This causes large-scale cooling of the ocean surface. The cooler ocean surface modifies the moisture content of the atmosphere across the Pacific and can cause shifts in the path of jet streams that intensifies rainfall in some places and causes droughts in others.

These weather effects tend to include floods in northern Australia, Indonesia, and southeast Asia and, in contrast, drought in the American southwest. In North America, cooler and stormier conditions often occur across the Pacific Northwest while the weather becomes warmer across the southern US and northern Mexico.

In the spring, the tropic Pacific essentially resets itself and starts building toward whatever condition will happen in the following winter, be it another La Niña or possibly an El Niño. For the time being, forecasters expect the current La Niña to persist through February.

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La Niña Times Three

Photo, posted March 10, 2007, courtesy of Gail via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Climate Change And Crops | Earth Wise

December 22, 2021 By EarthWise Leave a Comment

A new NASA study published in the journal Nature Food looks at the impact of global climate change on food crops. According to the study, declines in global crop yields are likely to become apparent by 2030 if high greenhouse gas emissions continue.

The study used advanced climate and agriculture models to predict the effects of projected increases in temperature, shifts in rainfall patterns, and elevated surface carbon dioxide concentrations from human-caused greenhouse gas emissions.

These climate changes would make it more difficult to grow corn in the tropics but would actually expand wheat’s growing range. The reduction in corn yields could be as much as 24% by late in the century. Corn Is grown all over the world and large quantities are produced in countries nearer to the equator. As temperatures rise in countries such as the US, Brazil, and China, yields are likely to decline because of the increased stress on the plants.

Wheat, which grows best in temperate climates may see a broader area where it can be grown as temperatures rise, but these gains are likely to level off by mid-century.

Rising temperature is not the only factor influencing crop yields. Rising carbon dioxide levels have a positive effect on photosynthesis and therefore on crop yields, especially for wheat. But changing rainfall patterns and rising temperatures can affect the length of growing seasons and accelerate crop maturity. This can result in the production of less grain than in a longer development period.

The changing climate has complicated effects on the growth of breadbasket crops and will be felt worldwide.

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Global Climate Change Impact on Crops Expected Within 10 Years, NASA Study Finds

Photo, posted September 8, 2004, courtesy of Lynn Ketchum/Oregon State University via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Wildfires And The Climate | Earth Wise

September 24, 2021 By EarthWise Leave a Comment

Scientists from the National Center for Atmospheric Research recently published a study analyzing the events that influenced the world’s climate in 2020. Among these were the pandemic-related lockdowns that reduced emissions and resulted in clearer air in many of the world’s cities.

While this was a significant event, the study found that something entirely different had a more immediate effect on global climate: the enormous bushfires that burned in Australia from late 2019 to 2020, producing plumes of smoke that reached the stratosphere and circled much of the southern hemisphere.

Those fires sprung up in September 2019 and lasted until March 2020. The fires burned more than 46 million acres (about 72,000 square miles), which is roughly the same area as the entire country of Syria. Thousands of homes and other buildings were lost.

Major fires inject so many sulfates and other particles into the atmosphere that they can disrupt the climate system, push tropical thunderstorms northward from the equator, and potentially influence the periodic warming and cooling of tropical Pacific Ocean waters known as El Nino and La Nina.

According to the study, the COVID-19 lockdowns actually had a slight warming influence on global climate, as a result of clearer skies enabling more heat to reach the earth’s surface. In contrast, the Australian bushfires cooled the Southern Hemisphere because the atmospheric particles reflected some of the incoming solar radiation back to space.

This summer, there have been raging wildfires in the western US and Canada, which have affected air quality in many parts of the nation and have been a serious health hazard. Undoubtedly, these fires are influencing the climate system as well in ways that we are still trying to understand.

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Bushfires, not pandemic lockdowns, had biggest impact on global climate in 2020

Photo, posted January 18, 2020, courtesy of BLM-Idaho via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Giant Marine Preserve | Earth Wise

May 4, 2020 By EarthWise Leave a Comment

The Seychelles islands are located east of Kenya, near the equator. Its beautiful beaches, virgin jungles, thriving coral reefs, and UNESCO-listed nature reserves are among the many attractions of the archipelago’s 115 islands. The larger inner islands are quite developed for tourists, studded with many luxurious five-star resorts. The natural wonders of the Seychelles are clearly its prime asset.

Given this, the Seychelles have now established 154,000 square miles of marine protected areas, fulfilling a pledge to protect nearly a third of its vast territorial waters. This is an area twice the size of Great Britain.

About half of the newly protected areas will be “no-take zones” in which economic activity such as fishing and mining will be prohibited. Only limited economic activities will be permitted in the other half of the protected areas.

The President of the Seychelles signed the decree establishing the marine reserve in mid-March. The reserve will help protect the nation’s fisheries resources and safeguard a host of species including endangered sea turtles, sharks, and the Indian Ocean’s last remaining population of dugongs, which are marine mammals similar to manatees.

The funding for managing and protecting the new marine reserves will come from what is termed a debt-for-nature deal. It is an agreement that was worked out with the help of The Nature Conservancy that allows the country to restructure nearly $22 million in foreign debt in exchange for protecting marine resources and enacting climate adaptation measures.

This major expansion of the Seychelles’ marine protected area is a major step in the conservation of the archipelago’s biodiversity. The success of that conservation will ultimately depend upon enforcement, public-private partnerships, and innovative management.

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Seychelles Creates a Marine Reserve Twice the Size of Great Britain

Photo, posted October 22, 2017, courtesy of Falco Ermet via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Refugee Corals

August 30, 2019 By EarthWise Leave a Comment

As climate change warms the ocean, subtropical environments are becoming more favorable for corals than the equatorial waters where they traditionally thrived. As a result, drifting coral larvae are settling and growing in new regions.

According to new research in the journal Marine Ecology Progress Series, the number of young corals on tropical reefs has declined by 85% over the past 40 years. At the same time, the numbers on subtropical reefs has doubled.

Only certain types of coral can reach these new subtropical locations. That depends on how far the microscopic larvae can swim and drift on currents before they exhaust their limited fat stores. Thus, the reef ecosystems that develop have new blends of species that have previously never coexisted. It is not clear how long it will take for the new systems to reach equilibrium.

Coral reefs are complicated systems that depend on the interplay between species to enable their healthy functioning. Apart from the corals themselves, there are the coraline algae that symbiotically coexist with them. How all of this will play out in these evolving ecosystems is unknown.

In the meantime, the research has found that these refugee corals are settling at latitudes up to 35 degrees both north and south of the equator. It is no longer so clear what constitute native species in the reefs. It remains to be seen whether new reefs in subtropical oceans can support the incredible biodiversity seen in tropical reefs. But ultimately, these changing ecosystems could potentially bring new resources and opportunities, such as fishing and tourism, to places where they never existed before.

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Coral Reefs Shifting Away from Equatorial Waters

Photo, posted March 22, 2011, courtesy of Simone Lovati via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change And Harsh Winters

July 15, 2019 By EarthWise Leave a Comment

In recent years, there have been some unusually harsh winters in North America and Central Europe. This past January, the Midwestern US experienced extreme cold temperatures. We have all become familiar with the term ‘polar vortex’ and its role in sending cold air to middle latitudes and it is generally agreed that unusual behavior by the jet stream is the primary cause of the extreme winter weather.

For years, climate researchers around the world have been investigating the question as to whether the increasingly common wandering of the jet stream is a product of climate change or is a random phenomenon associated with natural variations in the climate system.

The jet stream is a powerful band of westerly winds over the middle latitudes that push major weather systems from west to east. These days, the jet stream is increasingly faltering. Instead of blowing along a straight course parallel to the equator, it sweeps across the Northern Hemisphere in massive waves, producing unusual intrusions of Arctic air into the middle latitudes.

Atmospheric researchers at the Alfred Wegener Institute in Germany have now developed a climate model that can accurately predict the frequently observed winding course of the jet stream. The breakthrough combines their global climate model with a new machine learning algorithm on ozone chemistry. Using their new combined model, they can now show that the jet stream’s wavelike course in winter and subsequent extreme weather outbreaks are the direct result of climate change. The changes in the jet stream are to a great extent caused by the decline in Arctic sea ice, according to the results of the investigations. The results are not surprising but there is now a detailed model to support the hypothesis.

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