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The Effect of AGW on Oceans

Posted on: October 1, 2019





An article in Nature published in September 2019 [LINK] summarizes and explains a new United Nations IPCC Special Report on the impact of climate change on the world’s oceans [LINK] . The Nature summary says that “World’s oceans are losing power to stall climate change. United Nations report predicts more powerful storms, increased risk of flooding and dwindling fisheries if greenhouse-gas output doesn’t fall”. The full text of the Nature article is included below. This post is a critical commentary on some aspects of the claims made in these documents. 


  1. OCEAN ACIDIFICATION: With respect to ocean acidification, it is claimed that CO2 in fossil fuel emissions is absorbed by the oceans thus “becoming more acidic, which threatens the survival of coral reefs and fisheries”. In a related post [LINK]  it is shown that in the 60-year period 1955-2015, inorganic CO2 concentration in the ocean has gone up at an average rate of 0.002 MM/L (millimoles per liter) per year but that correlation analysis fails to show that these changes can be related to fossil fuel emissions. In this study, in terms of ppm by weight, the CO2 concentration of the ocean had increased from 88ppm to 110ppm for a gain of 22ppm at a rate of 0.367ppm per year. During this period fossil fuel emissions increased from 7.5 gigatons/year of CO2 (GTY) to 36.1GTY with cumulative emissions since 1851 rising from 258 GT to 1,505 GT with a total amount contributed in this period of 1,247 GT equivalent to an increase of 0.91 ppm of CO2 in the ocean if all of the emissions dissolve into the ocean. Therefore, the observed rise of 22pm cannot be explained in terms of fossil fuel emissions. Natural emissions of CO2 from from geological sources in the ocean itself such as plate tectonics, submarine volcanism, hydrothermal vents, methane hydrates, and hydrocarbon seepage must be considered in the study of changes in oceanic inorganic CO2 concentration.
  2. OCEAN HEAT CONTENT: Measurement data show a rising trend in ocean heat content since the 1950s and AGW theory describes this change as human caused attributable to Anthropogenic Global Warming (AGW) by way of fossil fuel emissions of the industrial economy. However, in a related post [LINK] it is shown that the warming of the ocean is not uniform, as one would expect if the source of the extra heat is the CO2 forcing of the atmosphere, but contains large regional differences and also a vertical difference that implies greater heating in the deeper ocean. Climate science explains this anomalous situation in terms of ocean currents as in this statement from the NOAA “Exceptions include the central South Pacific and the western tropical Indian Ocean, a feature that the State of the Climate authors attributed to an unusual eastward flow of warm surface water back toward the other side of the basin. Because of the Earth’s rotation, prevailing surface winds and currents near the equator are generally westward” [LINK] . However, there is an extreme atmosphere bias in this assessment because it does not take into account known large geothermal heat sources of the ocean that provide a more rational explanation for the non-uniform heat distribution. These sources are described in related posts [LINK] and their importance in terms of climate can be seen in their extreme effects in paleo climatology described in related posts [LINK] [LINK] . That submarine volcanism and the Pacific Ring of Fire are irrelevant in understanding changes in ocean heat content is not a credible position in the context of the enormous geological footprint of these features of the ocean [LINK] .




Nature article about the impact of AGW on the oceans. September 2019 [LINK]

The world’s oceans have long helped to stave off climate change by absorbing heat and carbon dioxide from the atmosphere. But that is changing, with devastating consequences for humanity in the coming decades, leading researchers warn in a high-level report commissioned by the United NationsThe rate at which oceans are warming has doubled since the early 1990s, and marine heat waves are becoming more frequent and intense ― trends that are reshaping ocean ecosystems and fueling more powerful storms. And as the oceans absorb CO2, they are becoming more acidic, which threatens the survival of coral reefs and fisheries. The special report on oceans and ice by the Intergovernmental Panel on Climate Change (IPCC) warns that without steep cuts to greenhouse-gas emissions, fisheries will falter, the average strength of hurricanes will increase and rising seas will increase the risk of flooding in low-lying areas around the globe.
The hard truths of climate change — by the numbers
The oceans “can’t keep up” with humanity’s greenhouse-gas output, says Ko Barrett, vice-chair of the IPCC and a deputy assistant administrator at the US National Oceanic and Atmospheric Administration in Washington DC. “The consequences for nature and humanity are sweeping and severe.”

More than 100 scientists from 30 countries contributed to the report. The IPCC released a 42-page summary of the analysis on 25 September at a meeting in Monaco.

High-water mark
The report projects that sea levels could rise by up to 1.1 metres by 2100 if greenhouse gas emissions continue to rise. That is about 10 centimetres more than the IPCC estimated in its last comprehensive report on the global climate, which it released in 2013.

Richard Alley, a geoscientist at Pennsylvania State University in University Park, says that the latest report’s sea-level rise projections are conservative. That’s because scientists still aren’t certain about when rising temperatures might trigger a rapid collapse of ice sheets, particularly in western Antarctica. If that happens, ocean levels will rise much faster than the IPCC’s latest estimate.
Attack of the extreme floods
“Sea-level rise could be a little less, a little more, or a lot more” than the latest report predicts, Alley says. “But it’s not going to be a lot less.”

Those rising seas will increase the risk of flooding during storms, the report says, and high tides will become more frequent and severe. By 2050, flooding events that now occur once per century are likely to occur annually in many coastal cities and islands ― even with sharp emissions cuts.

But the report does make it clear that humanity can blunt the worst effects of climate change over the very long term. It projects that the sea level could be from 0.6 metres to 5.4 metres higher in 2300, depending in large part on whether and how quickly countries move to curb greenhouse-gas emissions.

“We’re going to get sea-level rise for centuries,” says Michael Oppenheimer, a climate scientist at Princeton University in New Jersey and coordinating lead author on the report’s chapter on sea-level rise. “The question is whether it’s going to be manageable or not.”
‘Ecological grief’ grips scientists witnessing Great Barrier Reef’s decline
A draft version of the special report estimated that rising seas could displace 280 million people worldwide by 2100. The IPCC removed that figure from the final analysis, after scientists decided that they had misinterpreted the findings of an earlier study, Oppenheimer says.

Changing patterns
The IPCC report also examines the fate of the planet’s ice ― which it says will continue to shrink in the coming decades.

In the Arctic, where sea ice melts every summer and freezes every winter, the annual summer minimum extent has decreased by nearly 13% per decade since 1979. That rate of change is probably unprecedented in at least 1,000 years, the IPCC says. About 20% of the Arctic’s permafrost is vulnerable to abrupt thaw, followed by sinking of the soil left behind. By the end of the century, that could increase by half the area of the Arctic that is covered by small lakes.

And mountainous regions with small glaciers ― from the Andes to Indonesia ― could lose 80% of their ice by 2100.

The report’s overarching message, Barrett says, is that climate change is affecting water from the tops of Earth’s highest peaks to the depths of its oceans, and ecosystems are responding. Without steep emissions cuts, the total biomass of marine animals could shrink by 15% by 2100, and commercial fisheries could see their maximum catch decrease by up to 24%.
Trapped: why 300 scientists are locking themselves in Arctic ice
Such changes are already playing out in many locations, says Kathy Mills, a fisheries ecologist with the Gulf of Maine Research Institute in Portland. In the North Atlantic Ocean, for example, rising temperatures have sent right whales north in search of cooler waters. And that increases the animals’ chances of getting caught in lobster-trap lines.

“These ocean changes mean big problems for the future of people,” says Jane Lubchenco, a marine ecologist at Oregon State University in Corvallis and former head of the US National Oceanic and Atmospheric Administration.

Lubchenco is an adviser to the High Level Panel for a Sustainable Ocean Economy, which released its own report on climate change and the world’s oceans on 23 September. The analysis identifies a range of actions — including promoting renewable energy and sustainable fisheries, curbing marine shipping emissions and protecting coastal ecosystems — that could reduce global carbon emissions and limit the effects of climate change.

Lubchenco says those actions would also bolster coastal economies and help lift people out of poverty. “The reality is that the ocean is central to solving many problems,” she says. “The situation is quite dire and quite gloomy, but it is not hopeless.”


3 Responses to "The Effect of AGW on Oceans"

[…] in deep ocean heat are ultimately ascribed to atmospheric changes caused by fossil fuel emissions. [LINK] [LINK] [LINK] […]


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