Water Vapor Feedback

3 months ago 39

Earth's Energy Imbalance is now about four times as high as it was a decade ago, as illustrated by the above image, by Eliot Jacobson. As a result, feedbacks are starting to kick in with greater ferocity.

Water vapor feedback

One such feedback is the water vapor feedback. The temperature rise results in more evaporation, i.e. more water vapor and heat will enter the atmosphere, much of which will return to the surface in the form of precipitation, but some will remain in the atmosphere, as there will be 7% more water vapor for every 1°C warming. As illustrated by the image below, created with NOAA data, surface precipitable water was at 27.181 kg/m² in August 2024, a record high for this month.

[ surface precipitable water through August 2024 ]

How much more water vapor currently is in the atmosphere compared to pre-industrial depends on how much the temperature has risen since pre-industrial. The February 2024 temperature was 1.76°C above 1885-1915, which could be as much as 2.75°C above the pre-industrial temperature. A 2.75°C rise corresponds with almost ⅕ more water vapor in the atmosphere.

More water vapor and heat in Arctic

The temperature rise also comes with stronger wind. An earlier post points at a study that found increased kinetic energy in about 76% of the upper 2,000 meters of global oceans, as a result of intensification of surface winds since the 1990s.

Stronger wind speeds up ocean currents, enabling more ocean heat to move to the Arctic, while stronger wind also contributes to more rain falling closer to the Arctic, in line with prevailing ocean currents and wind patterns. As a result, both heat and water vapor will increase in the Arctic.

This will in turn further increase the temperature rise in the Arctic, since water vapor is a potent greenhouse gas, while more water vapor also results in less hydroxyl, thus extending methane's lifetime.

The resulting temperature rise in the Arctic also reduces the snow and ice cover, further amplifying the temperature rise in the Arctic.

Huge temperature rise

High levels of methane are already present over the Arctic and the water vapor feedback makes things worse. Additionally, more ocean heat entering the Arctic Ocean can destabilize hydrates at the seafloor and cause methane eruptions, resulting in huge amounts of methane entering the atmosphere over the Arctic.

Changes to ocean currents and the Jet Stream can at times hold back some of these impact, but such changes on the other hand can also amplify the impact. As Earth's Energy Imbalance keeps rising, huge amounts of heat accumulate in oceans, and part of this heat can - due to storms - abruptly be pushed into the Arctic, which can be further facilitated by the formation of a freshwater lid at the surface of the North Atlantic that enables more ocean heat to travel underneath this lid to the Arctic Ocean, along the path of prevailing ocean currents and wind patterns.

A huge temperature rise could unfold by 2026 as the joint result of changes in the atmosphere, changes in surface and cloud albedo, changes in wind patterns & ocean currents, and further developments, e.g. in a cataclysmic alignment, the next El Niño threatens to develop while sunspots are higher than expected. Sunspots are expected to reach a peak in the current cycle in July 2025.

The joint impact could cause the clouds tipping point to get crossed, adding an abrupt further 8°C to the rise, which could in turn cause the water vapor tipping point to get crossed, which means that from then on the increase in water vapor alone would suffice to keep increasing the temperature, in a runaway greenhouse process in which evaporation could cause a global surface temperature rise of several hundred degrees Celsius and make our planet as inhospitable as Venus, as this study concludes and as discussed at this post.

[ click on images to enlarge ]

A 2020 study led by Jorgen Randers concludes that the world is already past a point-of-no-return for global warming, as self-sustained thawing of the permafrost will continue for hundreds of years, even if global society did stop all emissions of man-made greenhouse gases immediately, due to a combination of declining surface albedo (driven by decline of the Arctic snow and ice cover), increasing amounts of water vapor in the atmosphere (driven by higher temperatures), and changes in concentrations of further greenhouse gases in the atmosphere (driven by changes in sinks and sources of carbon dioxide and methane such as thawing permafrost), as illustrated by the image on the right, from an earlier post.

Climate Emergency Declaration

The situation is dire and the precautionary principle calls for rapid, comprehensive and effective action to reduce the damage and to improve the situation, as described in this 2022 post, where needed in combination with a Climate Emergency Declaration, as discussed at this group.