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October GeoRoundUp: the best of the Earth sciences from around the web

October GeoRoundUp: the best of the Earth sciences from around the web

Drawing inspiration from popular stories on our social media channels, major geoscience headlines, as well as unique and quirky research, this monthly column aims to bring you the latest Earth and planetary science news from around the web.

Major story

In October, the UN Intergovernmental Panel on Climate Change (IPCC) released a landmark report and summary statement that detailed the severe consequences for our environment and society if global warming continues unabated. The special report, also known as the SR15, was compiled by 91 authors from 40 countries, and cites more than 6,000 peer-reviewed studies.

“There’s no doubt that this dense, science-heavy, 33-page summary is the most significant warning about the impact of climate change in 20 years,” said Matt McGrath an environment correspondent for BBC News.

The  EGU announced its support of the IPCC report in a statement published last month. In this address, EGU President Jonathan Bamber said: “EGU concurs with, and supports, the findings of the SR15 that action to curb the most dangerous consequences of human-induced climate change is urgent, of the utmost importance and the window of opportunity extremely limited.”

The IPCC was first commissioned to produce this report by the UN Convention on Climate Change following the Paris agreement, where world leaders pledged to limit global warming to well below 2ºC above pre-industrial levels and “pursue efforts” towards 1.5ºC. The goal of the report was to better understand what it would take for the world to successfully meet this 1.5ºC target and what the consequences would be if we are unable to reach this goal.

The report illustrates the two different outcomes that would arise from limiting global warming to 1.5ºC or allowing temperatures to rise to 2ºC.

While a half-degree doesn’t come across like a pronounced difference, the report explains that additional warming by this degree could endanger tens of millions more people across the world with life-threatening heat waves, water shortages, and coastal flooding from sea level rise. This kind of warming would also increase the chances that coral reefs and Arctic sea ice in the summer would disappear. These are just a few of the impacts detailed in the report. Recently, Carbon Brief has also produced an interactive graphic that does a deep dive into how climate change at 1.5ºC, 2ºC and beyond will impact different regions and communities around the world.

It should be noted that while limiting warming to 1.5ºC is the better of the two pathways, it still isn’t optimal. For example, under this warming threshold, the authors of the report project that global  sea levels would still rise, coral reefs would decline by 70-90%, and more than 350 million additional people would be exposed to severe drought.

Furthermore, the report goes on to explain what action (and just how much of it) would be necessary to limit warming to 1.5ºC. An article from the Guardian perhaps put it best: “there’s one simple critical takeaway point: we need to cut carbon pollution as much as possible, as fast as possible.

The report authors emphasise that limiting warming would require a massive international movement to reduce emissions and remove carbon dioxide from the atmosphere; and additionally this effort would need to happen within the next few years to avoid the most severe outcomes. They warn that if greenhouse emissions are still released at their current rate, the Earth’s temperature may reach 1.5ºC some time between 2030 and 2052, and reach more than 3ºC by 2100. Even more so, they concluded that the greenhouse gas reduction actions currently pledged by various countries around the world are still not enough to limit warming to 1.5ºC.

Measures to reach this temperature target include reducing global carbon dioxide emissions by 45% from 2010 levels by 2030, and reach a ‘net-zero’ by 2050. and making dramatic investments in renewable energy. They conclude that 70-35% of the world’s electricity should be generated by renewables like wind and solar power by 2050. By that same time, the coal industry would need to be phased out almost entirely.

Moreover, the authors say that we would need to expand forests and develop technology to suck carbon dioxide from the atmosphere. The report notes that climate action needs to be taken on an individual level as well, such as reducing the amount of meat we eat and time we spend on flying airplanes.

The authors report that we have the technology and means to limit warming by 1.5ºC, but they warn that the current political climate could make reaching this goal less likely.

“Limiting warming to 1.5ºC is possible within the laws of chemistry and physics but doing so would require unprecedented changes,” said Jim Skea, Co-Chair of IPCC Working Group III, in an IPCC press release.

Still have questions about the recent report? The IPCC has released a comprehensive FAQ and Carbon Brief has published an in-depth Q&A that addresses questions such as why the panel released the report, why adaptation is important, what the reaction has been, and what’s next.

What you might have missed

BepiColombo approaching Mercury. Credit: ESA/ATG medialab; Mercury: NASA/JPL

Last month the science media was also abuzz with a series of space agency news. On 20 October, the European-Japanese mission BepiColombo successfully launched from French Guiana, starting its seven-year long journey to Mercury, the smallest and least explored terrestrial planet in the Solar System. The probe is poised to be the third mission to travel to Mercury.

Once it arrives in 2025, the spacecraft will actually separate into two satellites, which will orbit the planet for at least one year. One satellite will investigate Mercury’s magnetic field while the other will take a series of measurements, including collecting data on the planet’s terrain, topography, and surface structure and composition. The researchers involved with the mission hope to learn more about Mercury’s origins and better understand the evolution of our solar system.

While one mission has started its journey, another’s has come to an end. Last month NASA’s planet-hunting Kepler space telescope has officially been retired after running out of fuel. Over its 9-year life span, the telescope has spotted more than 2,600 planets outside our solar system, many of which are possibly capable of sustaining life.

“As NASA’s first planet-hunting mission, Kepler has wildly exceeded all our expectations and paved the way for our exploration and search for life in the solar system and beyond,” said Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate in Washington. “Not only did it show us how many planets could be out there, it sparked an entirely new and robust field of research that has taken the science community by storm. Its discoveries have shed a new light on our place in the universe, and illuminated the tantalizing mysteries and possibilities among the stars.”

However, even though Kepler’s planet-scoping days are over, NASA’s new space observatory, the Transiting Exoplanet Survey Satellite (TESS) mission, which launched in April 2018, will continue the search for habitable worlds.

NASA’s Kepler space telescope, shown in this artist’s concept, revealed that there are more planets than stars in the Milky Way galaxy. Image credit: NASA

Links we liked

The EGU story

Earlier in October, we announced the winners of the 2019 EGU awards and medals: 45 individuals who have made significant contributions to the Earth, planetary and space sciences and who will be honoured at the 2019 EGU General Assembly next April. We have also announced the winners of the Outstanding Student Poster and PICO (OSPP) Awards corresponding to the 2018 General Assembly, which you can find on our website. Congratulations to all!

This month, we also opened the call for abstracts for the EGU 2019 General Assembly. If you are interested in presenting your work in Vienna in April, make sure you submit your abstract by 10 January 2019, 13:00 CET. If you would like to apply for a Roland Schlich travel grant to attend the meeting, please submit your abstract no later than 1 December 2018. You can find more information on the EGU website.

Interested in science and art? After successfully hosting a cartoonist and a poet in residence at last year’s annual meeting, we are now opening a call for artists to apply for a residency at the EGU 2019 General Assembly. The deadline for applications is 1 December. You can find more information about the opportunity online here.

And don’t forget! To stay abreast of all the EGU’s events and activities, from highlighting papers published in our open access journals to providing news relating to EGU’s scientific divisions and meetings, including the General Assembly, subscribe to receive our monthly newsletter.

How to make a planet habitable

How to make a planet habitable

Exoplanets without plate tectonics could harbour life, contrary to previous belief

For a planet to be habitable, it needs a stable climate. On Earth, the movement of tectonic plates ensures old crust is recycled and new crust is created and weathered. This cycling of rock consequently overturns the planet’s carbon, which keeps the climate in check.

While we have plate tectonics on Earth, many other rocky planets have what is called a ‘stagnant lid’. In this system, there is one solid plate wrapped around the planet, and the mantle circulates beneath it. The same recycling processes found on Earth don’t occur in these stagnant lid planets, preventing regulation of the carbon cycle and generating an inhospitable climate, or so scientists thought.

It is often claimed that plate tectonics is a requirement for a habitable climate, but research presented at the EGU General Assembly in Vienna suggests that some of these stagnant lid planets may be habitable after all.

Volcanic activity on stagnant lid planets could provide enough fresh rock for weathering to operate like it does on Earth, suggests Bradford Foley, a geologist from Pennsylvania State University in University Park, Pennsylvania. This means that simply burying the crust by lava flows could recycle enough CO2 to regulate the climate.

In their early history, the rocky surfaces of stagnant lid planets release gases that form an atmosphere. These young planets are also peppered with volcanoes that produce fresh, weatherable rock. Combined, these processes create a carbon cycle and, if the conditions are right, they can maintain a stable climate for long periods of time.

By modelling processes on stagnant lid planets that are similar in size to Earth, Foley was able to work out what conditions would create a habitable climate. The balance lies in striking the right amount of degassing, the process in which volcanoes release gas into the atmosphere. Not enough would lead to full surface glaciation, as too thin an atmosphere would make the planet extremely cold. On the other hand, too much degassing would generate a thick, CO2-rich atmosphere, leading to an incredibly hot environment.

There are two planetary budgets to take into account: carbon and heat. “We found a sweet spot, around Earth’s total amount of carbon to an order of magnitude less than that,” says Foley. That’s about 10 times less carbon than there is in Earth’s atmosphere, mantle and crust combined. Much lower, and there’s not enough of an atmosphere to keep the planet warm.

The other important consideration is the planet’s heat budget. As radioactive elements decay, they produce heat, and the more of these heat-producing elements a planet has, the bigger its heat budget. If a stagnant lid planet has fewer heat-producing elements than Earth, volcanic activity dies off pretty quickly and the planet cools off. “Without volcanism, the planet would most likely freeze over,” Foley adds. The more heat-producing elements there are, the longer volcanism can last. This means that, potentially, habitable climates could last longer too.

“Planets with two to two and a half times the heat budget for Earth can have potentially habitable climates lasting for three to four billion years, plenty enough time for developing life,” Foley explains.

According to Foley, the model could be used to guide future exoplanet missions. If we know how old a planet is and have information on its heat budget we can work out its chances of being habitable, says Foley. Both of these can be worked out using observations from Earth and could be used to create new targets for planetary exploration.

Lena Noack, a planetary scientist and Junior Professor at Free University Berlin who was not involved in the study, shared her thoughts on the research: “it shows, even though plate tectonics would typically always be considered as a better indicator for habitability, stagnant lid planets do not need to be ruled out. A good example is Mars; it was locally habitable early on in its history, but if it would just be a little bit larger, of Earth size as in Foley’s study, it is not difficult to imagine that it would be quite a habitable place at present day.”

By Sara Mynott

References: 

Foley,  B. Climate Stability and Habitability of Earth-like Stagnant Lid Planets. EGU General Assembly. 2018. 

Foley, B. and Smye, A. Carbon cycling and habitability of Earth-size stagnant lid planetsarXiv:1712.03614v1. 2017.