Tag Archives: carbon dioxide

Distant Super-Earth Exoplanet Has A Climate Perfect For Simple Life

While astrobiologists are increasingly hoping to find microbial life dwelling on or just beneath the surface of Mars, exoplanet hunters have been continually searching for habitable worlds far from our local corner of the Milky Way. Just recently, three Earth-like planets were discovered hovering 40 light-years away from us, and a new study, published in the journal Astrobiology, may have just described another.

Its roughly 40 percent larger than Earth, and its the outermost of five planets orbiting a star that is both smaller and cooler than our own Sun. Although its a lot further away 1,200 light-years, to be precise this new study suggests that the Kepler-62f may be able to sustain life.

First identified by the mechanical wunderkind that is the Kepler space observatory, little was known about it at the time. A team of researchers from the Universities of California Los Angeles (UCLA) and Washington turned to cutting-edge computer simulations in order to work out what it may be like to wander around on its surface.

We found there are multiple atmospheric compositions that allow it to be warm enough to have surface liquid water, Aomawa Shields, a National Science Foundation astronomy and astrophysics postdoctoral fellow in UCLAs department of physics and astronomy, and the studys lead author, said in a statement. This makes it a strong candidate for a habitable planet.

The relative sizes of recently discovered habitable-zone planets and Earth. From left to right: Kepler-69c, Kepler-62e, this studys Kepler-62f, and our own pale blue dot. NASA/Ames/JPL-Caltech

The shape of the planets orbital path was the first thing that needed to be calculated. To do so, the team used a renowned computer model named HNBody; this was combined with two tried-and-tested climate change models to simulate its possible climate configurations as it orbited its star.

The models assumed the atmosphere of Kepler-62f could be the same thickness as Earths all the way up to 12 times as thick. A variety of concentrations of carbon dioxide in the atmosphere were also considered, ranging from the same as Earths to up to 2,500 times that.

Based on what we know about microbial life, and considering the dimness of the alien star, Kepler-62f would only be completely habitable throughout its entire orbit if its atmosphere was 3 to 5 times thicker than our own, and it was composed entirely of carbon dioxide. This would ensure that a potent greenhouse effect would be in operation, which would warm the planet to habitable levels for microscopic life.

The most likely orbital parameters calculated by the models suggest that the planet would indeed by far away enough from its star to allow carbon dioxide to steadily accumulate in the atmosphere over time, as opposed to being blasted away by powerful solar radiation. Even if there was only an Earth-typical amount of carbon dioxide in the atmosphere, the temperatures would still go above waters freezing point for portions of the year.

The early Earth has a carbon dioxide-rich atmosphere thanks to prolonged volcanic activity. IM_photo/Shutterstock

Wherever you find water on Earth, there is life and such an atmospheric configuration would allow liquid water to be present at the surface. With water and carbon dioxide, photosynthesizing alien life, if it exists there, could one day convert Kepler-62fs atmosphere into one brimming with oxygen.

However, without a strong magnetic field, too much incoming solar radiation may render life at the surface impossible. Still, this somewhat damp and warm planet appears to be in the habitable zone, so thats certainly something worth noting.

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Read more: http://www.iflscience.com/space/distant-super-earth-exoplanet-has-climate-perfect-simple-life

Rising Atmospheric CO2 Has Lead To A Global “Greening” Effect

The rise in atmospheric CO2 over the past 100 or so years has been having some devastating effects. From the record temperatures being observed with increased frequency, to the melting of the Arctic ice, there is little doubt that the climate is indeed changing. But it seems that there has been another impact, as the world appears to have gotten greener. Even so, the authors note that the negatives of more CO2 in the atmosphere far outweigh the benefits.

A new study published in Nature Climate Change has found a massive increase in the growth of trees and plants, and concludes that this has been driven by the increase in concentration of atmospheric CO2. Using data from the NASA-MODIS and NOAA-AVHRR satellite sensors, an international team of 32 researchers from 24 institutions found that over the last 33 years, between 25 and 50 percent of Earths vegetated land has shown significant greening.

The planet has actually seen a significant increase in leaf cover around the world. Prof. R. Myneni/Boston University

If all green leaves on Earth werelaid out the area would cover around 32 percent of the entire planet, and the new study has shown that the dramatic increase in atmospheric CO2 from around 220 parts per million (ppm)at the start of the industrial revolution to 403 ppm has added the equivalent of enough leaves to cover the continental U.S. twice over.

But an increase in CO2 is not totally sufficient to entirely explain the observed greening across much of the land. Using computer models, the researchers calculate that while the greenhouse gas accounts for around 70 percent of the increase in growth, other factors are involved. They reckon that an increase in nitrogen in the system is responsible for around 9 percent of the growth, climate change is responsible for around 8 percent, and changes in land use clocks up about 4 percent.

Inevitably, the study has been seized upon by climate skeptics, some of whom argue that the increase in atmospheric CO2 is actually good for the planet due to this increase in growth of vegetation. Yet this effect diminishes over time, the researchers say, as plants acclimatize to the higher concentrations of CO2, and get limited by other factors such as water and nutrients. But obviously, there are other impacts from the increase in greenhouse gasses.

The increase in leaf cover would cover allof the continental U.S., twice. IVDMStock/Shutterstock

The fallacy of the contrarian argument is two-fold, explains Dr. Philippe Ciais, one of the co-authors of the study from the Laboratory of Climate and Environmental Sciences in Gif-surYvette, France. First, the many negative aspects of climate change, namely global warming, rising sea levels, melting glaciers and sea ice, more severe tropical storms, etc. are not acknowledged. Second, studies have shown that plants acclimatize, or adjust, to rising CO2 concentration and the fertilization effect diminishes over time.

Despite what many a climate denier might argue, this increase in CO2 uptake by plants is simply not going to be sufficient, and has actually already been factored in by the International Panel on Climate Change (IPCC) when they make their models. Not only that, but while CO2 is the most prominent greenhouse gas, it is not the only one we have to worry about. The warming planet has already started to thaw out the permafrost of the northern hemisphere, beginning the release of massive reserves of methane, and there is little plants can do with that.

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Read more: http://www.iflscience.com/environment/rising-atmospheric-co2-has-lead-greening-effect

What Would Happen To The Climate If We Stopped Emitting Greenhouse Gases Today?

Earth’s climate is changing rapidly. We know this from billions of observations, documented in thousands of journal papers and texts and summarized every few years by the United Nations’ Intergovernmental Panel on Climate Change. The primary cause of that change is the release of carbon dioxide from burning coal, oil and natural gas.

International climate talks in Lima this week are laying the foundation for next year’s UN climate summit in Paris. While negotiations about reducing emissions grind on, how much warming are we already locked into? If we stop emitting greenhouse gases tomorrow, why would the temperature continue to rise?

Basics of carbon and climate

The carbon dioxide that accumulates in the atmosphere insulates the surface of the Earth. It’s like a warming blanket that holds in heat. This energy increases the Earth’s surface average temperature, heats the oceans and melts polar ice. As consequences, sea level rises and weather changes.

Global average temperature has increased. Anomalies are relative to the mean temperature of 1961-1990. Finnish Meteorological Institute and Finnish Ministry of the Environment, Author provided

Since 1880, after carbon dioxide emissions took off with the Industrial Revolution, the average global temperature has increased about 1.5F (0.85C). Each of the last three decades has been warmer than the preceding decade, as well as warmer than the entire previous century.

The Arctic is warming much faster than the average global temperature; ice in the Arctic Ocean is melting and the permafrost is thawing. Ice sheets in both the Arctic and Antarctic are melting. Ecosystems on both land and in the sea are changing. The observed changes are coherent and consistent with our theoretical understanding of the Earth’s energy balance and simulations from models that are used to understand past variability and to help us think about the future.

A crack in Antarctica’s Pine Island Glacier. NASA Goddard Space Flight Center, CC BY

Slam on the climate brakes

What would happen to the climate if we were to stop emitting carbon dioxide today, right now? Would we return to the climate of our elders? The simple answer is no. Once we release the carbon dioxide stored in the fossil fuels we burn, it accumulates in and moves amongst the atmosphere, the oceans, the land, and the plants and animals of the biosphere. The released carbon dioxide will remain in the atmosphere for thousands of years. Only after many millennia will it return to rocks, for example, through the formation of calcium carbonate – limestone – as marine organisms’ shells settle to the bottom of the ocean. But on time spans relevant to humans, once released the carbon dioxide is in our environment essentially forever. It does not go away, unless we, ourselves, remove it.

If we stop emitting today, it’s not the end of the story for global warming. There’s a delay in temperature increase as the climate catches up with all the carbon that’s in the atmosphere. After maybe 40 more years, the climate will stabilize at a temperature higher than what was normal for previous generations.

This decades-long lag between cause and effect is due to the long time it takes to heat the the ocean’s huge mass. The energy that is held at the Earth by the increased carbon dioxide does more than heat the air. It melts ice; it heats the ocean. Compared to air, it’s harder to raise the temperature of water – it takes time, decades. However, once the ocean temperature is elevated, it adds to the warming of the Earth’s surface.

So even if carbon emissions stopped completely right now, as the oceans catch up with the atmosphere, the Earth’s temperature would rise about another 1.1F (0.6C). Scientists refer to this as committed warming. Ice, also responding to increasing heat in the ocean, will continue to melt. There’s already convincing evidence that significant glaciers in the West Antarctic ice sheets are lost. Ice, water, and air – the extra heat held on the Earth by carbon dioxide affects them all. That which has melted will stay melted – and more will melt.

Ecosystems are altered by natural and manmade occurrences. As they recover, it will be in a different climate from that in which they evolved. The climate in which they recover will not be stable; it will be continuing to warm. There will be no new normal, only more change.

Glacial ice loss over Greenland and Antarctica from 2003 to 2010.

Best of the worst case scenarios

In any event, it’s not possible to stop emitting carbon dioxide today, right now. Despite significant advances in renewable energy sources, total demand for energy accelerates and carbon dioxide emissions increase. I teach my students that they need to plan for a world 7F (4C) warmer. A 2011 report from the International Energy Agency states that if we don’t get off our current path, then we’re looking at an Earth 11F (6C) warmer. Our current Earth is just over 1F warmer, and the observed changes are already disturbing.

There are many reasons that we need to essentially eliminate our carbon dioxide emissions. The climate is changing rapidly; if that pace is slowed, the affairs of nature and human beings can adapt more readily. The total amount of change, including sea-level rise, can be limited. The further we get away from the climate that we have known, the more unreliable the guidance from our models and the less likely we will be able to prepare. The warmer the planet gets, the more likely reservoirs of carbon dioxide and methane, another greenhouse gas that warms the planet, will be released from storage in the frozen Arctic permafrost – further adding to the problem.

If we stop our emissions today, we won’t go back to the past. This is not reason, however, to continue with unbridled emissions. We are adaptable creatures, with credible knowledge of our climate’s future and how we can frame that future. We’re already stuck with some amount of guaranteed climate change at this point. Rather than trying to recover the past, we need to be thinking about best possible futures.

The Conversation

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