Originally published on
by firstname.lastname@example.org (Sam Carana) at Arctic News
|Summer insolation on the Northern Hemisphere in red and in langleys
per day (left axis, adapted from Walker, 2008). One langley is 1 cal/cm²
(thermochemical calorie per square centimeter), or 41840 J/m² (joules
per square meter), or about 11.622 Wh/m² (watt-hours per square meter).
In blue is the mean annual sea surface temperature, given as the difference
from the temperature over the last 1000 years (right axis, from Bova, 2021).
While temperatures rose rapidly, especially before the insolation peak was reached, the speed at which temperatures rose was moderated by the snow and ice cover, in a number of ways:
- snow and ice cause sunlight to get reflected back into space
- energy from sunlight is consumed in the process of melting snow and ice, and thawing permafrost
- meltwater from sea ice and runoff from melting glaciers and thawing permafrost cools oceans.
|[ from earlier post ]|
- Snow & Ice Cover Loss – A 2016 analysis by Ganapolski et al. suggests that even moderate anthropogenic cumulative carbon dioxide emissions would cause an absence of the snow and ice cover in the next Milankovitch cycle, so there would be no buffer at the next peak in insolation, and temperatures would contine to rise, making the absence of snow and ice a permanent loss.
- Brighter Sun – The sun is now much brighter than it was in the past and keeps getting brighter.
- Methane – Due to the rapid temperature rise, there is also little or no time for methane to get decomposed. Methane levels will skyrocket, due to fires, due to decomposition of dying vegetation and due to releases from thawing of terrestrial permafrost and from the seafloor as hydrates destabilize.
- No sequestration – The rapidity of the rise in greenhouse gases and of the associated temperature rise leaves species little or no time to adapt or move, and leaving no time for sequestration of carbon dioxide by plants and by deposits from other species, nor for formation of methane hydrates at the seafloor of oceans.
- No weathering – The rapidity of the rise also means that weathering doesn’t have a chance to make a difference. Rapid heating is dwarfing what weathering can do to reduce carbon dioxide levels.
- Oceans and Ozone Layer Loss – With a 3°C rise, many species including humans will likely go extinct. A 2013 post warned that, with a 4°C rise, Earth will enter a moist-greenhouse scenario. A 2018 study by Strona & Bradshaw indicates that most life on Earth would disappear with a 5°C rise. As temperatures kept rising, the ozone layer would disappear and the oceans would keep evaporating and eventually disappear into space, further removing elements and conditions that are essential to sustain life on Earth.
All this has implications for the interpretation of the Paris Agreement. At the Paris Agreement, politicians pledged to take efforts to ensure that the temperature will not exceed 1.5°C above pre-industrial levels.
So, what are pre-industrial levels? The ‘pre-‘ in pre-industrial means ‘before’, suggesting that ‘pre-industrial’ refers to levels as they were in times befóre (as opposed to when) the Industrial Revolution started. Carbon dioxide and methane levels actually started to rise markedly about 6000 years ago, as illustrated by above image, based on Ruddiman (2015).
A recent post suggests that the 1.5°C threshold was already crossed in 2012, i.e. well before the Paris Agreement was adopted by the U.N. (in 2015), while there could be a temperature rise of more than 3°C by 2026.
|[ from earlier post ]|
• Sunspots. We’re currently at a low point in the sunspot cycle. As the image on the right shows, the number of sunspots can be expected to rise as we head toward 2026, and temperatures can be expected to rise accordingly. According to James Hansen et al., the variation of solar irradiance from solar minimum to solar maximum is of the order of 0.25 W/m⁻².
In conclusion, there could be a huge temperature rise by 2026 and with a 3°C rise, humans will likely go extinct, which is a daunting prospect. Even so, the right thing to do is to help avoid the worst things from happening, through comprehensive and effective action as described in the Climate Plan.
• Seasonal origin of the thermal maxima at the Holocene and the last interglacial – by Samantha Bova et al. (2021)
• Palaeoclimate puzzle explained by seasonal variation (2021)
• Important Climate Change Mystery Solved by Scientists (news release 2021)
• Milankovitch (Orbital) Cycles and Their Role in Earth’s Climate – by Alan Buis (NASA news, 2020)
• Milankovitch cycles – Wikipedia
• Late Holocene climate: Natural or anthropogenic? – by William Ruddiman et al. (2015)
• Critical insolation–CO2 relation for diagnosing past and future glacial inception – by Andrey Ganapolski et al. (2016)
• Co-extinctions annihilate planetary life during extreme environmental change – by Giovanni Strona & Corey Bradshaw (2018)
• Earth is on the edge of runaway warming
• IPCC AR5 Synthesis Report — Figure 2.8
• IPCC AR5 Report, Summary For Policymakers
• Radiative forcing of carbon dioxide, methane, and nitrous oxide: A significant revision of the methane radiative forcing – by M. Etminan et al.
• When Will We Die?
• Possible climate transitions from breakup of stratocumulus decks under greenhouse warming – by Tapio Schneider et al.
• A World Without Clouds
• How close are we to the temperature tipping point of the terrestrial biosphere? – by Katharyn Duffy et al.
• What Carbon Budget?
• Overshoot or Omnicide?
• Confirm Methane’s Importance
• Arctic Ocean invaded by hot, salty water
• Greenhouse gas levels keep rising at accelerating rates