Ocean Heating and Acidification: Difference between revisions
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===== How climate change is intensifying hurricanes ===== | |||
[https://grist.org/extreme-weather/how-climate-change-is-intensifying-hurricanes/ by Amal Ahmed 7/7/25 Grist] | |||
Extreme weather seems to make the headlines almost every week, as disasters increasingly strike out of season, break records, and hit places they never have before. | |||
===== Rising surface salinity and declining sea ice: A new Southern Ocean state revealed by satellites ===== | |||
[https://www.pnas.org/doi/10.1073/pnas.2500440122 by Alessandro Silvano 30/6/25 PNAS] | |||
For decades, the surface of the polar Southern Ocean (south of 50°S) has been freshening—an expected response to a warming climate. This freshening enhanced upper-ocean stratification, reducing the upward transport of subsurface heat and possibly contributing to sea ice expansion. | |||
===== Is a monster web of ocean currents headed for collapse? The race is on to find out ===== | |||
[https://www.nature.com/articles/d41586-025-01885-4?utm_source=bluesky&utm_medium=organic_social&utm_content=null&utm_campaign=CONR_JRNLS_AWA1_GL_PCOM_SMEDA_NATUREPORTFOLIO by Tim Kalvelage 18/6/25 nature] | |||
Although it doesn’t look like it, the Arctic waters are balmy in February, relative to the air temperatures, which can fall below −30 °C. On the screen of Stephens’s remote control, the pancake-shaped floes show up in the thermal images as dark circles, whereas open water and thin ice glow bright orange, indicating energy escaping from the ocean into the frigid polar air. | |||
===== Arctic Ocean acidifying up to four times as fast as other oceans, study finds ===== | |||
[https://www.theguardian.com/environment/2022/sep/29/arctic-ocean-acidifying-up-to-four-times-as-fast-as-other-oceans-study-finds by Karen McVeigh 29/9/22 The Guardian] | |||
The ocean, which absorbs a third of all of the carbon dioxide in the atmosphere, has grown more acidic because of fossil fuel use. Rapid loss of sea ice in the Arctic region over the past three decades has accelerated the rate of long-term acidification, according to the study, published in Science on Thursday. | |||
===== Greener green and bluer blue: Ocean poleward greening over the past two decades ===== | |||
[https://www.science.org/doi/10.1126/science.adr9715 by Marine Ecology 19/6/25 Science] | |||
The oceans are becoming greener toward the poles and bluer in the subtropics. Zhao et al. report measurements of ocean color made by satellites between 2003 and 2022 showing that a disparity in chlorophyll abundances is causing this trend, signaling a profound shift in the distribution of plankton biomass (see the Perspective by Kudela). This shift, which is most pronounced in the Northern Hemisphere, could cascade to higher trophic levels and cause unforeseen impacts on fisheries and national economies. | |||
===== Earth’s oceans are storing record-breaking amounts of heat ===== | |||
[https://www.sciencenews.org/article/earth-oceans-storing-heat-record-breaking-amounts?fbclid=IwAR1amUzydB1CS6NtKa9DDPbpE4BSyHTnsDqxDyR0wvVR6vvTotjLqqnkTLk Science News 01/13/21 Maria Temming] | |||
Water temperature measurements from around the globe indicate that the total amount of heat stored in the upper oceans in 2020 was higher than any other year on record dating back to 1955, researchers report online January 13 in Advances in Atmospheric Sciences. Tracking ocean temperature is important because warmer water melts more ice off the edges of Greenland and Antarctica, which raises sea levels (SN: 4/30/20) and supercharges tropical storms (SN: 11/11/20). | |||
Researchers estimated the total heat energy stored in the upper 2,000 meters of Earth’s oceans using temperature data from moored sensors, drifting probes called Argo floats, underwater robots and other instruments (SN: 5/19/10). The team found that upper ocean waters contained 234 sextillion, or 1021, joules more heat energy in 2020 than the annual average from 1981 to 2010. Heat energy storage was up about 20 sextillion joules from 2019 — suggesting that in 2020, Earth’s oceans absorbed about enough heat to boil 1.3 billion kettles of water. | |||
=====Increasing ocean stratification over the past half-century===== | |||
28 September 2020 Guancheng Li, Lijing Cheng, Jiang Zhu, Kevin E. Trenberth, Michael E. Mann & John P. Abraham | |||
<embed>https://www.nature.com/articles/s41558-020-00918-2</embed> | |||
Seawater generally forms stratified layers with lighter waters near the surface and denser waters at greater depth. This stable configuration acts as a barrier to water mixing that impacts the efficiency of vertical exchanges of heat, carbon, oxygen and other constituents. Previous quantification of stratification change has been limited to simple differencing of surface and 200-m depth changes and has neglected the spatial complexity of ocean density change. Here, we quantify changes in ocean stratification down to depths of 2,000 m using the squared buoyancy frequency N2 and newly available ocean temperature/salinity observations. We find that stratification globally has increased by a substantial 5.3% [5.0%, 5.8%] in recent decades (1960–2018) (the confidence interval is 5–95%); a rate of 0.90% per decade. Most of the increase (~71%) occurred in the upper 200 m of the ocean and resulted largely (>90%) from temperature changes, although salinity changes play an important role locally. | |||
=====Ocean carbon uptake widely underestimated===== | |||
<embed>https://phys.org/news/2020-09-ocean-carbon-uptake-widely-underestimated.html?fbclid=IwAR2qI43GkNU3i-w6SQ9la1sp1s9VG-715KBYEgPlWXKa_lcNyFjyoKjpl4o</embed>SEPTEMBER 4, 2020 by University of Exeter | |||
Previous estimates of the movement of carbon (known as "flux") between the atmosphere and oceans have not accounted for temperature differences at the water's surface and a few metres below. | |||
The new study, led by the University of Exeter, includes this—and finds significantly higher net flux of carbon into the oceans. | |||
It calculates CO2 fluxes from 1992 to 2018, finding up to twice as much net flux in certain times and locations, compared to uncorrected models. | |||
=====Harmful algae blooms in Arabian Sea linked to Himalayas melting===== | =====Harmful algae blooms in Arabian Sea linked to Himalayas melting===== | ||
[https://www.thethirdpole.net/2020/06/22/harmful-algae-blooms-in-arabian-sea-linked-to-himalayas-melting/?fbclid=IwAR1h9BSxHUjhpZKVAJ0XPKw1cdLlrhzyBQhXMsrDCdMiyN_yopa6kQ43GYw the Third Pole.Net TV Padma, June 22, 2020] | |||
As snow and ice melt in the Himalayan mountains, the winter winds that blow down from them are becoming warmer and more humid, the researchers say. This alters the currents of the Arabian Sea and distribution of nutrients – and in turn the marine food chain, with fish struggling in the new conditions. This is happening at a much faster rate than that predicted by global models, the study says. | As snow and ice melt in the Himalayan mountains, the winter winds that blow down from them are becoming warmer and more humid, the researchers say. This alters the currents of the Arabian Sea and distribution of nutrients – and in turn the marine food chain, with fish struggling in the new conditions. This is happening at a much faster rate than that predicted by global models, the study says. | ||
=====Climate velocity reveals increasing exposure of deep-ocean biodiversity to future warming===== | =====Climate velocity reveals increasing exposure of deep-ocean biodiversity to future warming===== | ||
<embed> https://www.nature.com/articles/s41558-020-0773-5#article-info </embed> | <embed> https://www.nature.com/articles/s41558-020-0773-5#article-info </embed> | ||
