Tag Archives: Mitigating

Is the Arctic Ocean Mitigating or Intensifying Global Warming? – Cyworthy

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Greenhouse gases play a crucial role in trapping heat in the atmosphere, and one significant gas found beneath the ocean floor is methane. This gas is often locked in an icy form known as methane hydrate. When methane hydrate begins to decompose or melt, methane gas is released into the ocean, potentially exacerbating global warming. Factors like thawing permafrost, tectonic activity, tidal shifts, and sea level changes can also trigger methane release from sediments. Despite ongoing research, scientists are still unraveling how these triggers will react to future climate changes.

Researchers have proposed that future global warming might accelerate the influx of methane into the oceans. To explore this hypothesis, they examined an ancient global warming episode that occurred approximately 56 million years ago, known as the Paleocene-Eocene Thermal Maximum (PETM). During this period, temperatures in the Arctic Ocean occasionally soared above 20°C (68°F), serving as a valuable comparison to the current warming conditions we face today.

Once methane is released into seawater, its outcome largely depends on two biological processes. Currently, around 90% of the methane emitted from the ocean floor is consumed by tiny organisms called microorganisms through a process known as anaerobic methane oxidation. During this process, microorganisms use methane along with sulfate, resulting in the production of solid iron-sulfur minerals called pyrite. Anaerobic methane oxidation effectively traps methane in minerals, preventing it from escaping into the atmosphere, thereby transforming the ocean into a reservoir, or sink, for methane.

However, excessive methane can overwhelm the sulfate-dependent cycle. In such cases, another group of microorganisms consumes methane along with oxygen through a process called aerobic methane oxidation. This process removes carbon dioxide, a potent greenhouse gas, from the ocean. While today, about 10% of oceanic methane consumption occurs via aerobic oxidation, this ratio may have differed in geological history.

To investigate the balance of anaerobic versus aerobic methane oxidation during the PETM, researchers analyzed sediments retrieved from the Arctic ocean floor. As sediments accumulate on the ocean floor, they compact over time. Scientists can drill deep and extract cylindrical samples, known as cores, from this compacted sediment.

Within a sediment core, the age of the material increases with depth, meaning that younger sediments are found at the top and older sediments at the bottom. For this project, the team worked with cores sourced from the Arctic Ocean, containing sediments up to 100 million years old. They found evidence of PETM deposits at a depth of 386 meters (1,266 feet) within these cores.

Researchers noted that microbes leave behind distinctive carbon-based molecules called organic biomarkers during decomposition. These organic biomarkers accumulate in sediment layers on the seafloor. Different types of methane-consuming microorganisms produce distinct biomarkers, one for anaerobic and another for aerobic methane oxidation. By measuring the abundance of these biomarkers in sediment cores, the team was able to determine which microorganisms prevailed during the PETM.

The biomarker indicative of aerobic methane oxidation is Hop(17)21-ene. The researchers observed a four-fold increase in Hop(17)21-ene during the PETM. Conversely, the biomarkers associated with anaerobic methane oxidation, Glycerol dialkyl tetraether, decreased by half. These trends suggested a rise in aerobic methane oxidation and a decline in anaerobic processes, attributed to the release of significant amounts of methane during warming conditions, which overwhelmed the sulfate-dependent methane cycle.

To estimate carbon dioxide output from aerobic methane oxidation during the PETM, researchers identified another biomarker in the sediment core, Fitan. This compound, produced by organisms that consume carbon dioxide during photosynthesis, offers clues about historical carbon dioxide levels. The study revealed that during the PETM and long thereafter, carbon dioxide concentrations in the Arctic Ocean were four times greater than today’s levels. This indicates that the Arctic Ocean remained a long-term source of carbon dioxide to the atmosphere, even after the PETM period.

The research team proposed that the increased aerobic methane oxidation observed during the PETM could parallel current trends in the warming Arctic Ocean amid climate change. Their findings underscore the potential dangers of converting methane to carbon dioxide, which further warms the atmosphere, heats the oceans, and triggers additional methane release from the ocean floor—all contributing to a feedback loop that can escalate and hinder recovery efforts.

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Source: sciworthy.com

Many climate policies are ineffective in mitigating climate change

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Most political efforts to tackle climate change have had little effect

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Most climate policies fail to significantly reduce emissions and have little effect on halting climate change, meaning governments must work harder to find ways to actually make a difference.

Nicholas Koch Researchers from the Mercator Institute for the Global Commons and Climate Change in Berlin found this by assessing the impact of 1,500 climate policies implemented in 41 countries across six continents between 1998 and 2022.

The researchers began by using machine learning to identify moments when a country's emissions fell significantly compared to a control group of other countries not included in the analysis. They found 69 such emissions “breaks” and compared them to a database compiled by the Organisation for Economic Co-operation and Development (OECD) that tracks what climate policies were enacted and when.

Matching policy shifts with changes in emissions is not an exact science, but the team was able to identify 63 of these changes as being due to one or more policy interventions that took place within a two-year period before or after the change, to account for lagged or anticipated effects.

Each of the 63 breaks reduced carbon dioxide emissions by between 600 million and 1.8 billion tonnes, but the researchers found that overall, most climate policies have fallen far short of this level of success. “There are many policies that have not led to significant reductions in emissions, and more policies do not necessarily lead to better outcomes,” Koch said.

Many policies fail because they are too specific, he says. For example, governments might subsidize the purchase of new electric cars, but most cars on the road are not electric, so the impact is minimal. One measure that seems to be very effective is a total ban, for example stopping the use of coal for electricity generation, but these are always used in conjunction with others, making it hard for the team to identify whether they work in isolation.

Politicians are looking for a one-size-fits-all policy mix, but they're out of luck: there's nothing that works for all sectors. Pricing seems to be the most effective tool, especially in reducing emissions in commercial industries, but it's not the only solution, Koch says. “We've found that the most frequently used policy tools – subsidies and regulations – are not enough,” he says. “Only in combination with price-based tools like carbon prices, energy taxes, can we achieve significant emissions reductions.” In other words, people will only reduce their emissions if it hurts their wallets.

“A key value of this paper is that it identifies clear changes in emissions in specific sectors and countries.” Matthew Patterson The researcher, from the University of Manchester in the UK, points out that the OECD's database of policy change has some limitations because the government documents it draws from are not reported consistently around the world, but he says it is the best available for the purposes of this study.

“We've known for some time that climate policies work best in combination, but this study gives us more specific information about which combinations work and in what circumstances,” Patterson says. This will allow us to more aggressively pursue these “breaks” to address the emissions gap and create the policy combinations that most effectively address emissions.

Marion Dumas Researchers at the London School of Economics and Political Science say that while the study should be useful to policymakers, looking first at emissions trends – or the results – and then working backwards to understand the causes may not capture the full reality of policy interventions.

“This is a very interesting approach, but there is a lot of uncertainty as to how to simulate the likely outcomes. [emissions] “You need to map out the trajectory and then identify the tipping points,” Dumas said, adding that a two-year gap around the tipping point may be too short and underestimates the real impact of more gradual, longer-term policy changes.

“It's important not to overinterpret the headline results, which suggest that very few policies will reduce emissions.” Robin Rambo The researchers, from Imperial College London, say small emissions reductions that their team's methods didn't detect could add up to big differences.

Of course, a larger issue in identifying the most effective measures is that policymaking doesn't take place in a vacuum, and specific policies must be acceptable to the general public. “The political dynamics will determine whether that combination can be implemented in any given country or sector,” Patterson says.

“We know this is going to be very difficult politically,” Koch said, “but the good news is that in general it's possible to put policies in place to achieve these very ambitious goals.”

topic:

  • Climate change measures/
  • Carbon Emissions

Source: www.newscientist.com