natural variability

Global Stilling | Earth Wise

October 20, 2022 By EarthWise Leave a Comment

During the summer of 2021, much of Europe experienced a “wind drought” – wind speeds in many places were about 15% below average. In the UK in particular, winds were unusually calm and wind energy production was dramatically reduced.

Globally, wind speeds have been dropping by about 2.3% per decade since the 1970s. In 2019, however, global average windspeeds actually increased by about 6%. The question is whether a trend of slowing winds – so-called global stilling – is associated with climate change or is just natural variability in action.

Wind results from uneven temperatures in air masses. Much of the world’s wind comes from the difference between the cold air at the poles and the warm air at the tropics. Because the Arctic is warming much faster than the tropics, it is possible that winds will continue to decline around the world.

Another factor people cite is the increase in surface roughness. The number and size of urban buildings continues to increase, which acts as a drag on winds.

Some models predict that wind speeds will decrease over much of the western U.S. and East Coast, but the central U.S. will see an increase. Experts do not all agree about what is happening with global winds. Many believe that the observed changes to date have been within the range of variability. Furthermore, some places have been windier than usual.

All of this really matters for many reasons. Europe is increasingly dependent upon wind power as an alternative to fossil fuels. A 10% drop in wind speed results in a 30% drop in energy generation. Whatever their cause may be, wind droughts cannot be ignored.

**********

Web Links

Global ‘Stilling’: Is Climate Change Slowing Down the Wind?

Photo, posted June 28, 2008, courtesy of Patrick Finnegan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Climate Change And The World’s Fisheries | Earth Wise

March 10, 2022 By EarthWise Leave a Comment

According to a new study, approximately 70% of the world’s oceans could be suffocating from a lack of oxygen by 2080 as a consequence of climate change. This has the potential to impact marine ecosystems all around the world.

The study, which was recently published in the journal Geophysical Research Letters, is the first to use climate models to predict how and when deoxygenation will occur throughout the world’s oceans outside of its natural variability.

According to the findings, significant and potentially irreversible deoxygenation of the ocean’s middle depths began occurring last year. The models predict that deoxygenation will begin affecting all zones of the ocean by 2080.

According to the study’s models, mid-ocean depths are already losing oxygen at unnatural rates. Globally, the ocean’s middle depth – known as the mesopelagic zone – is home to many of the world’s commercially fished species. This makes these new findings a potential harbinger of economic hardship, seafood shortages, and environmental disruption.

Just like land animals, aquatic animals need oxygen to breathe. As climate change warms the oceans, the water holds less oxygen and is more buoyant than cooler water. This leads to less mixing of oxygenated water near the surface with deeper waters, which naturally contain less oxygen. Warmer water also raises oxygen demand among living organisms, resulting in less availability for marine life.

The researchers also found that oceans closer to both the North Pole and the South Pole are particularly vulnerable to deoxygenation. While they are not yet sure why, accelerated climate warming could be the culprit.

These findings should add new urgency to climate change mitigation efforts.

**********

Web Links

Climate change has likely begun to suffocate the world’s fisheries

Photo, posted January 28, 2019, courtesy of Joseph Gage via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

People And The Earth’s Increasing Heat | Earth Wise

September 23, 2021 By EarthWise Leave a Comment

A new study by Princeton University and the National Oceanic and Atmospheric Administration had found clear evidence that human activity is the primary cause of the significant increase in heat stored in our planet. In fact, the study found that there is less than a 1% chance that natural variability is the sole cause of the increase.

The researchers looked at data from satellite observations to determine the amount of energy received by the earth and the amount reflected and emitted by the Earth. In a balanced physical system, the amount of incoming energy should equal the amount of outgoing energy. But the earth’s system is not balanced at this point. More energy is coming in than going out, which is driving changes in the climate system. There have been other studies looking at the human influence on the climate, but this new study is the first to examine a 20-year continuous satellite energy balance record to see if natural fluctuations in the climate system or human activities is the primary driver for the significant change in the planet’s energy balance.

The study examined 50 different climate models to look at this energy balance under scenarios where there was no human influence. These include changes in the sun’s output, volcanic eruptions, variations in pollution aerosols, and more.

The results, to no great surprise, are that increasing greenhouse gases over the last twenty years is by far the most important driver for the energy imbalance. This imbalance is what is driving rising temperatures, increasing sea levels, and causing other climate changes.

**********

Web Links

Human activities responsible for rapid increase in Earth’s heat

Photo, posted May 6, 2021, courtesy of Marlis Borger via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change And The South Pole | Earth Wise

August 10, 2020 By EarthWise Leave a Comment

According to a study led by researchers at Ohio University, the South Pole has warmed more than three times the global average over the past 30 years. While the warming was driven by natural tropic climate variability, the researchers argue that rising greenhouse gas emissions likely intensified the warming.

The climate in the antarctic has some of the largest ranges in temperature during the year. Some regions, like most of West Antarctica and the Antarctic Peninsula, experienced warming during the late 20th century. But the South Pole, which is located in the remote and high-altitude interior of the continent, actually cooled until the 1980s. The South Pole, as the study highlights, has warmed substantially ever since.

For the study, which was recently published in the journal Nature Climate Change, the researchers analyzed climate models and weather station data at the South Pole. They found that, between 1989 and 2018, the South Pole had warmed by 1.8 degrees Celsius. This warming trend of 0.6 degrees Celsius per decade is three times the global average.

According to the study, the robust warming of the Antarctic interior has been mainly driven by the tropics. Warm ocean temperatures in the western tropical Pacific Ocean have altered the winds in the South Atlantic, increasing the delivery of warm air to the South Pole. These atmospheric changes are an important part of what’s driving the climate anomalies in the region.

But the researchers argue that the warming trends are unlikely a result of natural climate change alone. The effects of anthropogenic – or human-caused – climate change in addition to the natural changes have combined to make this one of the strongest warming trends globally.

**********

Web Links

Extreme warming of the South Pole

Photo, posted February 7, 2011, courtesy of Eli Duke via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Europe Is Warming Faster Than Predicted

October 9, 2019 By EarthWise Leave a Comment

A new study has found that Europe is warming faster than even climate models projected. The number of summer days with extreme heat in Europe has tripled since the 1950s, while the number of days with extreme cold has decreased by factors of two or three depending on the region.

According to climate scientists at the Swiss Federal Institute of Technology in Zurich, the climate trends are much larger than what would come from natural variability and are a clear signal of climate change. Extremely hot days in Europe have become hotter by an average of more than 4 degrees Fahrenheit while extremely cold days have warmed by more than 5 degrees. The research examined data from weather stations across Europe from 1950 to 2018. Over 90% of the stations recorded increasing temperatures over time, a percentage much too high to be purely from natural climate variability. The results also showed that the region was warming even faster than climate models projected.

The research results come after an extremely hot summer in Europe. Southern France hit 114.8 degrees, a new record, in June. Germany, the Netherlands, and Belgium all recorded all-time national temperature highs. The National Oceanic and Atmospheric Administration recently announced that July was the hottest month ever recorded.

European summers and winters will only grow hotter in the coming years as climate change accelerates. The rapidly increasing temperatures will impact cities and people that are unprepared for them and pose real risks for residents in the coming decades. Extreme heat is dangerous because it stresses the human body, potentially leading to heat exhaustion or heat stroke.

**********

Web Links

Europe warming faster than expected due to climate change

Photo, posted July 30, 2011, courtesy of Marcel de Jong via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change And Heat Waves

February 3, 2017 By EarthWise

2016 was the hottest year on record and saw many extreme weather events. How much of what happened resulted from climate change has yet to be assessed. However, the analysis of 2015 – which was the hottest year on record up until last year – has been presented in a special publication by the American Meteorological Society.

The Ocean As A Heat Sink

December 15, 2016 By EarthWise

From 1998 until 2013, scientists observed a slowing in the rate of global mean surface warming. In other words, global temperatures were not rising as quickly as before. This quickly became known as the “global warming hiatus.”