Saturday, September 15, 2018

Hurricane Moderation


Hurricane Moderation

By Stephen Salter

The formation of a hurricane depends on many factors, including atmospheric water vapour, distance from the equator and the recent history of wind patterns. But an essential requirement is a high sea surface temperature. To get from a tropical storm to the lowest category of hurricane requires a temperature of 26.5°C. We can moderate hurricanes, or even prevent them, by reducing water temperature.

A useful start to any engineering project is the estimation of all the energy flows. One cubic metre of air at a temperature of 30°C can hold about 30 grams of water vapour. The energy to evaporate this is about the same as in 13 grams of TNT, enough for a nasty anti-personnel mine. A cubic kilometre of such air contains the same energy as the Hiroshima bomb. Hurricanes can be hundreds of kilometres in diameter and so contain tens of thousands of Hiroshimas. If you have read this far you will know about the billions of lost dollars and thousands of deaths from this amount of energy.

Most of the hurricanes that reach America (with the exception of Harvey), start on the African side of the Atlantic near Cape Verde and grow as they move west. We can use Google Earth to measure the hurricane breeding area. The US National Weather Service gives a warm water depth of 45 metres. To cool this volume by 2°C in 200 days needs more than 600 times the mean US electricity power generation. If you want to moderate a hurricane tomorrow, today is much too late. You should have started last November.

All this heat has come from the sun. Some could be reflected back out to space by clouds. The reflectivity of clouds was studied by Sean Twomey. He flew over many clouds, scooped samples and measured the solar energy reflected from their tops. He showed that reflectivity depends on the size distribution of drops. Lots of small drops reflect more than the same amount of liquid water in fewer, larger ones. In typical conditions, doubling the cloud drop number increases reflectivity by a bit over 0.05.

Making cloud drops needs a high humidity but also some kind of ‘seed’ called a condensation nucleus on which to start growth. There are thousands of condensation nuclei per cubic centimetre of air over land but fewer in air over mid ocean, often less than 50. John Latham suggested that the salt residues left from the evaporation of a spray of sub-micron drops of sea water would be excellent condensation nuclei. They would be moved from the sea surface by turbulence to produce a fairly even distribution upwards through the marine boundary layer to where clouds form.


The condensation nuclei could be produced by wind-driven sailing vessels cruising along the hurricane breeding areas getting energy from their motion through the water. We can make spray by pumping water through very small nozzles etched in the silicon wafers used for making microchips. The main technical problem is that sea water is full of plankton much larger than nozzles. This can be filtered using ultra-filtration technology with back-flushing, originally developed for removing polio viruses from drinking water. Each vessel would produce 0.8 micron diameter drops at 1017 a second.

[ part-image from larger Wikipedia map ]
Spray operations would depend on the pattern of sea surface temperatures as measured by satellites. We want the trajectory of temperature rises through the year from November to the following July to be those that an international panel of meteorologists think will give a desirable rainfall pattern from ‘gentle’ tropical storms.

Most ships are made in quite small numbers. An exception was the Flower class corvettes built for the Royal Navy during World War II. If we index-link the 1940 cost to today we can predict that in mass production each spray vessel would cost $4 million. With assumptions which have not yet been rejected by hurricane experts, we think that controlling the Atlantic hurricane breeding paths would need about 100 vessels. With typical ship lifetime the annual ownership and maintenance cost would be about $40 million. If these figures and recent estimates of the cost of hurricane damage are correct the benefit-to-cost ratio is quite attractive.

Because of official UK Government policy updated in May 2018 the project is privately funded.

Rising temperatures are increasing the amount of water vapor in the atmosphere at a rate of 7% more water vapor for every 1°C warming. This is further speeding up warming, since water vapor is a potent greenhouse gas. Over the coming years, a huge amount of additional water vapor threatens to enter the atmosphere, due to the warming caused by albedo changes in the Arctic, methane releases from the seafloor, etc., as described at this page.

The situation is dire and calls for comprehensive and effective action, as described at the Climate Plan.

Added below is a box from an earlier post with hurricane damage mitigation proposals.


Hurricane Damage Mitigation

A 2014 study by scientists led by Mark Jacobson calculates that large turbine arrays (300+ GW installed capacity) could diminish peak near-surface hurricane wind speeds by 25–41 m/s−1 (56–92 mph) and storm surge by 6–79% AND provide year-round clean and renewable electricity.

How many electric cars will be ready to move into Miami to provide emergency support in the wake of Hurricane Irma?

Storms can cause power outages, electricity poles can get damaged. Electricity poles can also be a traffic hazard (i.e. collisions can occur even if the pole hasn't fallen down, especially when streetlights fail). When damaged, power lines hanging off poles constitute electrical shock hazards and they can cause fires to ignite and wildfires to start.

Storms can also cause damage to backup generators and to fuel storage tanks, making it hard for emergency services to give the necessary support. Electric cars can supply electricity where needed, e.g. to power necessary air conditioning, autoclave and emergency equipment, such as in hospitals. After a tsunami hit Japan in 2011, electric cars moved in to provide electricity from their batteries, as described in many articles such as this one.

Wind turbines and solar panels are pretty robust. Hurricane Harvey hit the Papalote Creek Wind Farm near Corpus Christi, Texas. The wind farm had little or no damage, there was just a short delay in restarting, mostly due to damage to power lines. The Tesla roof that doubles as solar panels is much stronger than standard roofs. Have a look at this video.

Join the Renewables group at facebook!
Clean and renewable energy can provide more stable, robust and safe electricity in many ways. Centralized power plants are vulnerable, in that all eggs are in one basket, while there can be long supply and delivery lines. Many of the benefits of clean and renewable energy are mentioned on above image.

Furthermore, there are ways to lower sea surface temperatures. The image on the right shows the very high sea surface temperature anomalies on August 28, 2017.

Note the colder area (blue) in the Gulf of Mexico. Hurricane Harvey cooled the sea surface as water evaporated and warm moisture was added to the atmosphere. The cyclonic force also mixed colder water below the surface with warmer water at the surface, resulting in colder water at the surface. The combination image below shows the difference between August 20, 2017, and August 30, 2017.

[ click on images to enlarge ]

A number of geoengineering methods can be used to reduce sea surface temperatures and thus reduce the intensity of hurricanes. Methods include upwelling associated with ocean fertilization and with ocean tunnels, marine cloud brightening and increasing and brightening bubbles in the wake of vessels, as discussed at the geoengineering group at facebook.

Besides cooling the sea surface, there's also the upwelling of nutrients that can help combat ocean stratification. Warm water holds less oxygen than cold water. As the water warms, it also tends to form a layer at the surface that does not mix well with cooler, nutrient-rich water below, depriving phytoplankton of some of the nutrients needed in order for phytoplankton to grow (and take up carbon).

Some of these methods are also discussed at this 2011 page, which also mentions that more research is needed into the impact of such methods. Of course, possible application should go hand in hand with dramatic reductions in emissions including a rapid shift to 100% clean and renewable energy.

thesolutionsproject.org
Similarly, the necessary shift to clean and renewable energy in itself will not be enough to avoid catastrophic warming, and it should go hand in hand with further lines of action to remove pollution and to cool the Arctic Ocean, as described at the Climate Plan.


Links

• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html

• How much warming did and could people cause?
https://arctic-news.blogspot.com/p/how-much-warming-did.html

• AccuWeather predicts economic cost of Harvey, Irma to be $290 billion
https://www.accuweather.com/en/weather-news/accuweather-predicts-economic-cost-of-harvey-irma-to-be-290-billion/70002686

• After Disaster Hit Japan, Electric Cars Stepped Up
http://www.nytimes.com/2011/05/08/automobiles/08JAPAN.html

• In Big Test of Wind Farm Durability, Texas Facility Quickly Restarts After Harvey
https://www.wsj.com/articles/texas-wind-farm-back-online-1504294083

• Tesla Unveils Powerwall 2 & Solar Roof
https://www.youtube.com/watch?time_continue=802&v=4sfwDyiPTdU&fref=gc&dti=2372679678

• Taming hurricanes with arrays of offshore wind turbines, by Mark Z. Jacobson et al. (2014)
https://www.nature.com/nclimate/journal/v4/n3/full/nclimate2120.html

• The Solutions Project
http://thesolutionsproject.org

• Weakening of hurricanes via marine cloud brightening (MCB), by John Latham, Ben Parkes, Alan Gadian, Stephen Salter (2012)
https://onlinelibrary.wiley.com/doi/10.1002/asl.402/abstract

• Engineering Ideas for Brighter Clouds, by Stephen H. Salter, Thomas Stevenson and Andreas Tsiamis  (2014)
https://pubs.rsc.org/en/Content/Chapter/9781782621225-00131/978-1-78262-122-5

• Multiple Benefits Of Ocean Tunnels
https://arctic-news.blogspot.com/2015/02/multiple-benefits-of-ocean-tunnels.html

• Oxygenating the Arctic
https://arctic-news.blogspot.com/p/oxygenating-arctic.html

• Reducing hurricane intensity using arrays of Atmocean Inc.'s wave-driven upwelling pumps
https://www.youtube.com/watch?v=xlnR_GMNIGA

• Could bright, foamy wakes from ocean ships combat global warming?
https://www.sciencemag.org/news/2016/01/could-bright-foamy-wakes-ocean-ships-combat-global-warming


Monday, September 10, 2018

Blue Ocean Event

Blue Ocean Event as part of four Arctic tipping points

What will be the consequences of a Blue Ocean Event, i.e. the disappearance of virtually all sea ice from the Arctic Ocean, as a result of the warming caused by people?


Paul Beckwith discusses some of the consequences in the video below. As long as the Arctic Ocean has sea ice, most sunlight gets reflected back into space and the 'Center-of-Coldness' remains near the North Pole, says Paul. With the decline of the sea ice, however, the 'Center-of-Coldness' will shift to the middle of Greenland. Accordingly, we can expect the jet streams to shift their center of rotation 17° southward, i.e. away from the North Pole towards Greenland, with profound consequences for our global weather patterns and climate system, for plants and animals, and for human civilization, e.g. our ability to grow food.


Also see Paul's video below, The Arctic Blue-Ocean-Event (BOE). When? Then What?


Changing Winds

As global warming continues, the additional energy in the atmosphere causes stronger winds and higher waves.

As the Arctic warms up faster than the rest of the world, the jet streams are getting more out of shape, exacerbating extreme weather events.

The image on the right shows the jet stream crisscrossing the Arctic Ocean on September 10, 2018, with cyclonic wind patterns all over the place.

On the image below, Typhoon Mangkhut is forecast to cause waves as high as 21.39 m or 70.2 ft on September 14, 2018.


The inset on above image shows Typhoon Mangkhut forecast to cause winds to reach speeds as high as 329 km/h or 205 mph at 700 hPa (green circle), while Hurricane Florence is forecast to hit the coast of North Carolina, and is followed by Hurricane Isaac and Hurricane Helene in the Atlantic Ocean.


At 850 hPa, Typhoon Mangkhut reaches Instant Wind Power Density as high as 196.9 kW/m² on September 13, 2018, as illustrated by above image.

The situation is likely to get worse over the next few months, as this is only the start of the hurricane season and El Niño is strengthening, as illustrated by the image on the right.

The image below shows how the occurrence and strength of El Niño has increased over the decades.



Four Arctic Tipping Points

There are numerous feedbacks that speed up warming in the Arctic. In some cases, there are critical points beyond which huge changes will take place rather abruptly. In such cases, it makes sense to talk about tipping points.

1. The albedo tipping point

As Arctic sea ice gets thinner and thinner, a Blue Ocean Event looks more imminent every year. A Blue Ocean Event means that huge amounts of sunlight won't get reflected back into space anymore, as they previously were. Instead, the heat will have to be absorbed by the Arctic. 



At the other hemisphere, the sea ice around Antarctica is at its lowest extent for the time of the year, as illustrated by above image. Global sea ice extent is also at its lowest for the time of the year, as illustrated by the image below.

A Blue Ocean Event will not only mean that additional heat will have to be absorbed in the Arctic, but also that wind patterns will change radically and even more dramatically than they are already changing now, which will also make that other tipping points will be reached earlier. This is why a Blue Ocean Event is an important tipping point and it will likely be reached abruptly and disruptively.

2. The latent heat tipping point

Disappearance of the sea ice north of Greenland is important in this regard. The image on the right shows that most sea ice at the end of August 2018 was less than 1 meter thick.

The image below shows how the sea ice has been thinning recently north of Greenland and Ellesmere Island, an area once covered with the thickest multi-year sea ice. Disappearance of sea ice from this area indicates that we're close to or beyond the latent heat tipping point, i.e. the point where further ocean heat can no longer be consumed by the process of melting the sea ice.

[ The once-thickest sea ice has gone - click on images to enlarge ]
The amount of energy absorbed by melting ice is as much as it takes to heat an equivalent mass of water from zero to 80°C. Without sea ice, additional ocean heat will have to go somewhere else.


Above image shows how much sea surface temperatures in the Arctic have warmed, compared to 1961-1990. The image also shows the extent of the sea ice (white). In the image below, a large area has changed from sea ice to water twelve days later, showing how thin and fragile the sea ice is and how easily it can disappear as the water continues to warm.


As the Arctic is warming faster than the rest of the world, changes have been taking place to the jet streams on the Northern Hemisphere that make it easier for warm air and water to move into the Arctic. This means that warm water is increasingly entering the Arctic Ocean that can no longer be consumed by melting the sea ice from below.

Arctic sea ice extent has remained relatively large this year, since air temperatures over the Arctic Ocean have been relatively low in June and July 2018. At the same time, ocean heat keeps increasing, so a lot of heat is now accumulating underneath the surface of the Arctic Ocean.

[ click on images to enlarge ]
3. Seafloor Methane Tipping Point

As said above, Arctic sea ice has been getting thinner dramatically over the years, and we are now near or beyond the latent heat tipping point.

[ The Buffer has gone, feedback #14 on the Feedbacks page ]
This year, air temperatures over the Arctic Ocean were relatively low in June and July 2018, and this has kept Arctic sea ice extent larger than it would otherwise have been. As a result, a lot of heat has been accumulating underneath the surface of the Arctic Ocean and this heat cannot escape to the atmosphere and it can no longer be consumed by melting. Where will the heat go?

As the temperature of the Arctic Ocean keeps rising, more heat threatens to reach sediments at its seafloor that have until now remained frozen. Contained in these sediments are huge amounts of methane in the form of hydrates and free gas.

Melting of the ice in these sediments then threatens to unleash huge eruptions of seafloor methane that has been kept locked up in the permafrost for perhaps millions of years. Seafloor methane constitutes a third tipping point.

The image on the right features a trend based on WMO data. The trend shows that mean global methane levels could cross 1900 ppb in 2019.

Ominously, methane recently reached unprecedented levels. Peak levels as high as 3369 ppb on August 31, 2018, as shown by the image below on the right.

The next image on the right below shows that mean global levels were as high as 1905 ppb on September 3, 2018.

The third image below on the right may give a clue regarding the origin of these unprecedented levels.

More methane will further accelerate warming, especially in the Arctic, making that each of the tipping points will be reached earlier.

Less sea ice will on the one hand make that more heat can escape from the Arctic Ocean to the atmosphere, but on the other hand the albedo loss and the additional water vapor will at the same time cause the Arctic Ocean to absorb more heat, with the likely net effect being greater warming of the Arctic Ocean.

Additionally, more heat is radiated from sea ice into space than from open water (feedback #23).

How much warming could result from the decline of snow and ice cover in the Arctic?

As discussed, there will be albedo changes, there will be changes to the jet streams, and there will be further feedbacks, adding up to 1.6°C of additional global warming that could eventuate due to snow and ice decline and associated changes in the Arctic.

A further 1.1°C of warming or more could result from releases of seafloor methane over the next few years.

4. Terrestrial Permafrost Tipping Point

Additional warming of the Arctic will also result in further warming due to numerous feedbacks such as more water vapor getting into the atmosphere. Furthermore, more intense heatwaves can occur easier in the Arctic due to changes to jet streams. All this will further accelerate melting of the ice in lakes and in soils on land that was previously known as permafrost. This constitutes a fourth tipping point that threatens to add huge amounts of additional greenhouse gases to the atmosphere. Until now, the permafrost was held together by ice. As the ice melts, organic material in the soil and at the bottom of lakes starts to decompose. The land also becomes increasingly vulnerable to landslides, sinkholes and wildfires. All his can result in releases of CO₂, CH₄, N₂O, soot, etc., which in turn causes further warming, specifically over the Arctic.

In total, a temperature rise of 10°C threatens to occur in as little as a few years time.

The situation is dire and calls for comprehensive and effective action, as described in the Climate Plan.



Links

• Jet Stream Center-of-Rotation to Shift 17 degrees Southward from North Pole to Greenland with Arctic Blue Ocean Event
https://www.youtube.com/watch?v=bFme3C9e-cs

• It could be unbearably hot in many places within a few years time
https://arctic-news.blogspot.com/2016/07/it-could-be-unbearably-hot-in-many-places-within-a-few-years-time.html

• Feedbacks
https://arctic-news.blogspot.com/p/feedbacks.html

• Latent Heat
https://arctic-news.blogspot.com/p/latent-heat.html

• Albedo and more
https://arctic-news.blogspot.com/p/albedo.html

• Warning of mass extinction of species, including humans, within one decadehttps://arctic-news.blogspot.com/2017/02/warning-of-mass-extinction-of-species-including-humans-within-one-decade.html

• How much warming have humans caused?
https://arctic-news.blogspot.com/2016/05/how-much-warming-have-humans-caused.html

• The Threat
https://arctic-news.blogspot.com/p/threat.html

• Extinction
https://arctic-news.blogspot.com/p/extinction.html

• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html






Friday, August 24, 2018

The once-thickest Arctic sea ice has gone

The image below shows Arctic sea ice north of Greenland and around Ellesmere Island. This is the area where for thousands of years the sea ice has been the thickest, in many places remaining thicker than 5 meters (16.4 ft) throughout the year.

[ The once-thickest sea ice has gone - click on images to enlarge ]
The image is a compilation of NASA Worldview images over seven days, from August 14 through to August 21, 2018. The least cloudy areas have been selected from each image to get the best insight in the magnitude of this catastrophe.

The loss of this sea ice indicates that the buffer is gone. Sea ice acts as a buffer that absorbs heat, while keeping the temperature at the freezing point of water, about zero degrees Celsius. As long as there is sea ice in the water, this sea ice will keep absorbing heat, so the temperature doesn't rise at the sea surface.

Once the buffer is gone, further energy that enters the Arctic Ocean will go into heating up the water. The amount of energy absorbed by melting ice is as much as it takes to heat an equivalent mass of water from zero to 80°C.

[ The Latent Heat Buffer has gone, feedback #14 on the Feedbacks page ]
At the same time, decline of the snow and ice cover in the Arctic causes more sunlight to get reflected back into space, resulting in more energy getting absorbed in the Arctic Ocean.

[ Albedo Change, feedback #1 on the Feedbacks page ]

Numerous feedbacks are associated with sea ice loss. As the temperature difference between the Arctic and the Equator decreases, changes are taking pace to the Jet Stream that in turn trigger a multitude of further feedbacks, such as more extreme weather and a more scope for heat to enter the Arctic Ocean (see feedbacks page).


A further huge danger is that, as warming of the Arctic Ocean continues, heat will reach methane hydrates at the seafloor of the Arctic Ocean, causing them to get destabilized and release methane.

[ Seafloor methane, feedback #2 on the Feedbacks page ]
Adding up all warming elements associated with disappearance of the sea ice could result in additional global warming many times as much as the current global warming, all in a few years time.

Meanwhile, for the first time in human history, mean global methane levels as high as 1900 ppb have been recorded. The measurements were recorded by the MetOp-1 satellite on the morning of August 22, 2018, at 280 mb, 266 mb, 307 mb and 321 mb, as shown by the images below.


At 293 mb, MetOp-1 recorded an even higher level, i.e. mean global methane level was 1901 ppb on the morning of August 22, 2018.


The situation is dire and calls for comprehensive and effective action, as described in the Climate Plan.


Links

• It could be unbearably hot in many places within a few years time
https://arctic-news.blogspot.com/2016/07/it-could-be-unbearably-hot-in-many-places-within-a-few-years-time.html

• Feedbacks
https://arctic-news.blogspot.com/p/feedbacks.html

• Latent Heat
https://arctic-news.blogspot.com/p/latent-heat.html

• Albedo and more
https://arctic-news.blogspot.com/p/albedo.html

• How much warming have humans caused?
https://arctic-news.blogspot.com/2016/05/how-much-warming-have-humans-caused.html

• The Threat
https://arctic-news.blogspot.com/p/threat.html

• Extinction
https://arctic-news.blogspot.com/p/extinction.html

• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html




Sunday, August 19, 2018

Will August 2018 be the hottest month on record?


July and August are typically about 3.6ºC or 6.5ºF warmer than December and January. August is typically 1.8°C or 3.24ºF warmer than the average annual temperature. Above image shows how much higher the temperature was for selected months, compared to the annual global mean for the period 1980-2015. Will August 2018 be the hottest month on record?

Numerous temperature records have fallen across the world recently. Heat stress hazard is high under conditions of high surface air temperature and high relative humidity. When looking at heat stress hazards, it's therefore important to look at surface air temperatures over land, i.e. the temperature of the air above the land surface.

Fire hazard is high under conditions of hot and dry soil and strong wind. When looking at fire hazards, it's therefore important to look at land surface temperatures, reflecting how hot the surface of the Earth would feel to touch in a particular location. The map below shows land surface temperatures.


When calculating how much warmer it is now, a number of things must be taken into account:
  1. Baseline

    What baseline is used and how is the temperature at the baseline calculated? In the image at the top, the baseline is 1980-2015, which is a very recent period. When using a preindustrial baseline, anomalies could be more than 0.6°C higher than when using the 1951-1980 baseline that NASA normally uses.

  2. Surface temperatures or surface air temperatures?

    Above map shows land surface temperatures. As said above, this is different from surface air temperatures over land that show the temperature of the air above the land surface.

    Similarly, sea surface temperatures indicate the temperature of the water at the surface. Sea surface air temperatures, on the other hand, are slightly higher, they are measurements of the air temperature just above the surface of the water.

    NASA typically uses surface air temperatures over land, while using surface water temperatures over oceans. When instead using air temperatures globally, the temperature anomaly could be more than 0.1°C higher.
     
  3. Missing data

    How are missing data dealt with? To calculate the global mean on maps, NASA uses four zonal regions (90-24ºS, 24-0ºS, 0-24ºN, and 24-90ºN) and fills gaps in a region by the mean over the available data in that region. In datasets, however, missing data are typically ignored. This could make a difference of 0.2°C. Ignoring data for the Arctic alone could make a difference of 0.1°C.  
Depending on how the above three points are dealt with, the temperature in August 2018 may well be more than 3°C above the mean annual global temperature in 1750. The question is whether August 2018 will be warmer than August 2016, which was 2.3°C warmer than 1980-2015.

Anthropogenic Global Warming

Remember the Paris Agreement, when politicians pledged to take efforts to ensure that the temperature would not cross 1.5°C above preindustrial? Why did the Paris Agreement not specify a year for preindustrial? Perhaps the idea was that total anthropogenic global warming should not exceed 1.5°C. In other words, the warming that people had already caused by 1750, plus the warming people caused since 1750, plus the warming that is already baked in for the decades to come. The image below illustrates this idea and also shows that we're well above 1.5°C anthropogenic global warming.

[ click on images to enlarge ]
In the image below, temperatures have also been adjusted to better reflect a preindustrial baseline (1750), showing that temperatures were not higher than 1°C above preindustrial during the entire Holocene, until recently.


In a recent paper, James Hansen et al. conclude that temperatures also weren't more than 1°C above preindustrial during the previous interglacial, the Eemian, which implies that temperatures haven't been more than 1°C above preindustrial for the entire 200,000 years that modern people, i.e. the species homo sapiens, have existed, and that temperatures have only recently rising to levels more than 1°C above preindustrial. Quite likely, to find temperatures as high as today's, one would have to go back some 3 million years.

Fires over North America, August 2018

Fires can significantly influence temperatures in a number of ways. The images below show how fires boosted carbon dioxide, carbon monoxide and sulfur dioxide levels on August 19, 2018. Carbon dioxide and carbon monoxide both raise temperatures. On the other hand, sulfur dioxide lowers temperature by reflecting sunlight back into space.

  Top left: carbon monoxide as high as 51495 ppb 
  Top right: carbon dioxide as high as 836 ppm
  Bottom left: Smoke over North America
  Bottom right: sulfur dioxide as high as 1917.57 µg/m³
The image below illustrates to what extent smoke from fires boosted black carbon in the air over North America on August 23, 2018. Black carbon causes both cooling and warming. Black carbon shades the surface, somewhat cooling the surface of land and water, while it also absorbs heat, thus warming the air above the surface. Furthermore, black carbon causes warming by darkening the surface once it settles down. Studies have calculated that black carbon has a total net global warming effect of more than 1.1 W/m².


Dust and further aerosols

The impact of aerosols such as sulfur dioxide and dust is often overlooked. The image below shows that τ, i.e. light at 550 nm as a measurement of aerosol optical thickness due to dust aerosols, was as high as 4.0641 on June 16, 2018.


[ goats, from Wikipedia ]
Dust is one reason why temperatures didn't cross the 1°C above preindustrial mark during the peak of the recent Milankovitch cycle. A recent study calculates that the global annual mean surface temperature increases by 0.3°C for the mid-Holocene (6 ka), if the dust is completely removed.

Most dust appears to originate from the Sahara Desert, which lost its vegetation during the Holocene due to goats, according to this study, as people removed predators such as lions and tigers. As the Sahara lost its vegetation, the surface became more reflective, while dust further made that temperatures didn't rise as much as they otherwise would have.

Deforestation has caused a lot of carbon dioxide to be added during preindustrial times, and there is also the impact of black carbon aerosols, resulting from biomass and fossil fuel burning, which causes some 1.1W/m² warming today and some 0.2W/m² is coming from preindustrial activities.

In conclusion, temperatures would be a lot lower in the absence of human activities, while total anthropogenic global warming over the past few thousand years is much larger than most people think.

The situation is dire and calls for comprehensive and effective action, as described in the Climate Plan.


Links

• NASA - The Northwest is Running Hot and Dry
https://earthobservatory.nasa.gov/images/92601/the-northwest-is-running-hot-and-dry

• NASA GISS (Goddard Institute for Space Studies) Surface Temperature Analysis (GISTEMP)
https://data.giss.nasa.gov/gistemp

• NASA - Just Another Day on Aerosol Earth
https://earthobservatory.nasa.gov/images/92654/just-another-day-on-aerosol-earth

• Aerosols
https://arctic-news.blogspot.com/p/aerosols.html

• How much warming have humans caused?
https://arctic-news.blogspot.com/2016/05/how-much-warming-have-humans-caused.html

• How much warmer is it now?
https://arctic-news.blogspot.com/2018/04/how-much-warmer-is-it-now.html

• Extinction
https://arctic-news.blogspot.com/p/extinction.html

• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html