421.59 ppm: tracking weekly climate news

Welcome to our regular segment on new climate news stories you might have missed. The title refers to the daily average global concentration of carbon dioxide within the Earth’s atmosphere in parts per million (ppm). Meaning that for every million air particles, currently 421.59 of them are CO2.

Flowers bloom in Antarctica as it warms

In the first evidence of climate change accelerating ecosystem shifts on the icy continent, researchers have studied the striking expansion in the population of the two native Antarctic flowering plants – Antarctic hair grass (Deschampsia antarctica) and Antarctic pearlwort (Colobanthus quitensis).

These are the only two vascular plants (containing specialised tissue which distributes resources throughout the plant) that grow in Antarctica. They are found only on the coastal region of the Antarctic Peninsula; researchers studied their growth on Signy Island.

The study, published in Current Biology, found that climate warming since the 1950s has allowed the plants to expand in the last decade (2009-2018), despite a major cold “pulse” in 2012 after which air temperature warming resumed.

However, whilst the warming may benefit some native Antarctic plants, according to the researchers it will also lead to increased risk from plant invaders which could trigger irreversible biodiversity loss and induce changes to the fragile and unique ecosystems.

The yellow flowers of the antarctic pearlwort, growing between rocks.
Antarctic pearlwort (Colobanthus quitensis). Credit: Liam Quinn

Politics, society and tech shape the path of climate change

Climate change models and predictions rarely include data about politics and society, despite the fact they dictate climate policy and therefore the trajectory of greenhouse gas emissions.

Now, a computational modelling study has found that public perceptions of climate change, the future cost and effectiveness of climate mitigation and technologies, and how political institutions respond to public pressure, are all important factors in the degree to which climate will change over the 21st century. 

The researchers simulated 100,000 potential future pathways of climate policy and greenhouse gas emissions – using an integrated and multidisciplinary model that drew from data from a wide range of social, political and technical fields – to understand the probability of different temperature outcomes for future decades. The study was published in Nature.

Nuclear power might be key to least-cost, zero-emission electricity systems

Nuclear power generation can play a crucial role in helping the world to reach the key goal of zero carbon emissions by 2050, according to a new study,. Today, gaps in the energy that wind and solar provide are made up by power generated from natural gas, but for a zero-emission electricity system it is claimed we need more tools in our toolbox.

Using computer modelling, the researchers investigated the wind and solar resources of 42 countries to evaluate which would benefit from nuclear power’s ability to provide low-cost energy and replace natural gas as an energy source.

They found that countries with poor wind resources, such as Brazil, would benefit from the strategic use of nuclear power to enable a faster transition away from carbon. Whereas in countries which have the right geographic and climate conditions for generating lots of wind power, such as the US, nuclear would not need to be employed until the last remaining hurdles of decarbonisation needed to be overcome.

“Our analysis looked at the cheapest way to eliminate carbon dioxide emissions assuming today’s prices,” says author Dr Ken Caldeira from Carnegie’s Department of Global Ecology. “We found that at today’s price, nuclear is the cheapest way to eliminate all electricity-system carbon emissions nearly everywhere.

“However, if energy storage technologies became very cheap, then wind and solar could potentially be the least-cost path to a zero-emission electricity system.”

The research was published in Nature Energy.

A nuclear power plant with a wind turbine in front.
Credit: Sylvain Sonnet/Getty Images

“Blue Blob” near Iceland could slow glacial melting

A region of cooling water in the North Atlantic Ocean near Iceland, nicknamed the “Blue Blob”, has likely slowed the melting of the island’s glaciers since 2011, and may continue to do so until about 2050.

New research using climate models and field observations, published in Geophysical Research Letters, found that the cold water patch chilled the air over Iceland to slow ice loss, and predicts a temporary respite for Iceland’s glaciers.

However, without steps taken to mitigate climate change the glaciers could lose a third of their current ice volume by 2100, as ocean and air temperatures are predicted to increase between 2050 and 2100, leading to accelerated melting.

The origin and cause of the Blue Blob, which is located south of Iceland and Greenland, is still being investigated.

A glacier covered in snow.
A recent slowdown in the melting of Iceland’s glaciers is likely caused by a patch of unusually cold water in the North Atlantic Ocean. Credit: Finnur Pálsson

Seagrasses continue to release methane even after they die-off

Seagrass meadows are essential ecosystems – they protect coasts from erosion and sequester millions of tonnes of carbon dioxide from the atmosphere every year. However, they also form and emit the greenhouse gas methane and continue to do so even decades after they die, according to a new study.

Scientists investigated whether the methane from seagrass forms in a similar way as methane forms on land (from the decomposition of dead plant matter) but instead found the opposite. The findings were published in Proceedings of the National Academy of Sciences.

“In seagrass sediments, methane is formed solely from one class of organic compounds,” says author Dr Sina Schorn, of the Max Planck Institute for Marine Microbiology, Germany. “These so-called methylated compounds are produced by the seagrass plant itself. Specialised microorganisms, the methanogenic archaea, then convert these compounds into methane.”

Interestingly, the rates of methane production in dead seagrass meadows were found to be similar to those in living ones. This is because the researchers believe that the methylated compounds persist in the plant tissue for a very long time, as they could be detected in plant tissue that had died more than two decades ago.

“Currently, we are seeing a die-off of seagrass meadows worldwide which has a devastating effect on the coastal ecosystems,” explains senior author Dr Jana Milucka, head of the Greenhouse Gases Research Group at the Max Planck Institute.

“Our results caution that, whereas upon the death of the plant carbon dioxide from the atmosphere will no longer be sequestered and stored in the sediment as ‘blue carbon’, methane may still continue to be released.”

An underwater seagrass bed.
Seagrass meadow in the Mediterranean. Seagrass meadows are widespread and cover a total of close to 600,000 square kilometers worldwide, which is roughly equivalent to the area of France. Credit: HYDRA Marine Sciences GmbH

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