Articles » Environment Counts

Link between Milankovitch’s theory of orbital forcing and ice ages remains an open question

Posted on June 24, 2019August 13, 2019 by Geoff Zeiss

A seminal book by Milankovitch in 1941 proposed that the sequence of ice ages that has characterized long term changes in the Earth’s climate over the past hundreds of thousands of years was due to changes in the amount of solar radiation reaching the Earth as a result of small variations in the Earth’s orientation and orbit with respect to the sun. Since then research has shown that Milankovitch cycles by themselves do not determine the timing of glacial and interglacial cycles and that we still lack a unified mechanism that links changes in Earth’s orbit to ice ages.

Latest NASA research reveals several East Antarctica glaciers losing ice

Posted on December 12, 2018August 10, 2019 by Geoff Zeiss

In contrast to West Antarctica where several large glaciers have been losing ice for decades, East Antarctica glaciers have exhibited little evidence of ice loss but NASA’s latest detailed maps of East Antarctica ice velocity and elevation show that a number of glaciers have begun to lose ice over the past decade.

Emissions from electric power generation decoupled from economic growth in US

Posted on November 7, 2018August 10, 2019 by Geoff Zeiss

Between 2005 and 2017 the U.S. economy as measured by real GDP expanded by about 20 %. Over this same period, emissions from power generation dropped which is evidence of a decoupling between economic growth and power generation.

Increased methane in atmosphere sourced to fossil fuels and livestock

Posted on July 25, 2018August 17, 2019 by Geoff Zeiss

The source of the accelerating rise in atmospheric methane concentration since 2007 remains an open question. A recent study using satellite imagery suggests that the increase may be ascribed to increased fossil fuels and livestock sources in roughly equal measure.

Low cost sensor enables citizen scientists to measure and share urban air pollution data over the web

Posted on June 2, 2018August 10, 2019 by Geoff Zeiss

Based on the latest results from WHO air pollution is now the world’s largest single environmental health risk, linked to 12% of all global deaths. Citizen scientists can contribute to measuring air pollution using a low cost sensor measuring atmospheric particulate matter and share the measurements via open source geospatial web mapping software.

Decreasing oxygen in open ocean threatens biological diversity

Posted on January 12, 2018August 10, 2019 by Geoff Zeiss

Oxygen is fundamental to oceanic biological processes and its decline can cause major changes in ocean productivity and biodiversity. Over the past 50 years low oxygen zones in the open oceans have expanded by an area equivalent to half the size of Canada and hundreds of coastal sites now have low oxygen concentrations that limit the distribution and abundance of animal populations.

Evidence for sea level rise of 17 meters in less than 350 years

Posted on December 28, 2017August 10, 2019 by Geoff Zeiss

During the last deglaciation there was several episodes of rapid and substantial sea level rise. A recent study has found that during one of these, sea level rose by about 17 meters over a period that does not exceed 350 years, but could be as low as a century.

Greenhouse gas emissions from melting permafrost not yet significant

Posted on December 26, 2017August 10, 2019 by Geoff Zeiss

As the Earth warms, permafrost soils melt and this old carbon is released into the atmosphere as methane and CO2. Using radiocarbon dating of methane bubbles and soil organic carbon from lakes formed by melting thermafrost in Alaska, Canada, Sweden and Siberia combined with remote sensing it is found that methane and carbon dioxide releaed in the Arctic region during the past 60 years is much less than the CO2 contributed annually from anthropogenic and other sources.

Black carbon is the second most important anthropogenic contribution to climate warming

Posted on December 12, 2017August 10, 2019 by Geoff Zeiss

A reanalysis of the effect of black carbon emissions has found that it is second only to carbon dioxide emissions in its warming impact on the climate. Together carbon dioxide, black carbon, and methane emissions represent the anthropogenic sources with the largest impact on Earth’s climate.

Increase in extreme weather events confirmed by latest U.S. government report

Posted on August 15, 2017August 15, 2017 by Geoff Zeiss

There is strong evidence of marked changes in temperature extremes across the contiguous United States – extreme cold waves have become less common while extreme heat waves have become more common and heavy precipitation events in most parts of the United States have increased in both intensity and frequency. That is the conclusion of a report prepared by scientists from NOAA, NASA and other agencies.

From Our Files

Regional principal components for temperature and precipitation PNAS

Geospatial-temporal analysis reveals two trends in global climate during the last deglaciation

The last deglaciation was characterized by increases in surface temperatures of 10-15 °C punctuated by millennial-scale warming/cooling periods, pulses of increasing atmospheric carbon dioxide and asynchronously increasing methane. A geospatial-temporal variance analysis reveals a global warming trend correlating with rising CO2 on which is superimposed second trend millennial-scale regional warming/cooling periods associated with variation in the strength of the Atlantic overturning current.

Increase in extreme weather events confirmed by latest U.S. government report

Greenland ice core records reveal periods of rapid warming across globe during last deglaciation

Air bubbles in Greenland ice cores are analyzed to compare changes in Greenland surface temperature and atmospheric methane concentration during a rapid warming event lasting 200 years during the last deglaciation. It is found that changes in Greenland surface temperature and atmospheric methane emissions occurred essentially synchronously indicating that this warming event included the tropics.

Southern Ocean outgassing initial source of rising CO2 during the last deglaciation

During the first pulse of increasing atmospheric CO2 at the beginning of the last deglaciation the carbon-13 ratio dropped precipitously indicating that a source of the CO2 was a large pool of carbon of organic origin. Comparison with other data including the atmospheric carbon-14 record point at outgassing from Southern Ocean deep water as the source of the CO2 increase in this early period of the deglaciation.