Re: The urgent necessity to halt Greenland meltdown
John Nissen
here it isLetter: Greenland meltdown and the reasons it matters
From John Nissen, Chair of the Planetary Restoration Action Group, London W5, UK🙏DougSent from my iPhone (audio texting)On Jan 24, 2026, at 5:41 PM, John Nissen <johnnis...@gmail.com> wrote:Dear John,Re 1. Greenland meltwater causing at least as much meltwater being discharged from AntarcticaThe effect of Greenland meltwater on Antarctic glaciers can be clarified. The sea level rise in Antarctica would cause grounding line retreat for some major glaciers, thereby accelerating glacier discharge [1] [2]. This acceleration would add to existing acceleration from other causes. A sea level rise of over half a metre can be expected from Antarctic glaciers this century; see 60 cm in [3]. With over half a metre from Greenland further stimulating discharge from Antarctica, a total of well over one metre becomes likely this century.[Original queried text]The dynamics of the planet means that this meltwater would directly raise sea levels in Antarctica, causing glacier collapse and raising the sea level by well over a metre. Once started, further collapse would be impossible to stop.[Suggested replacement]Meltwater from Greenland would raise the sea level in Antarctica, causing some major glaciers to boost their discharge of ice. A number of glaciers are already in a critical condition, and their contribution to sea level rise could easily match that of Greenland, making a total of over a metre quite likely this century.[The whole paragraph]A prime reason for Trump’s interest in Greenland is to exploit its resources, as recognised by a Danish investment fund’s ‘huge appetite’ to invest in Greenland (FT, 18th Jan)”. However, treating Greenland as a resource prize while its ice sheet melts is reckless. Greenland’s ice sheet holds enough ice to raise the global sea level by over 7 metres; a partial collapse could release over half a metre this century. Meltwater from Greenland would raise the sea level in Antarctica, causing some major glaciers to boost their discharge of ice. A number of glaciers are already in a critical condition, and their contribution to sea level rise could easily match that of Greenland, making a total of over a metre quite likely this century.Kind regards, JohnP.S. For uniformity, the "11 billion USD per year" for SAI should be written in the same format as the "$700bn per year" estimated financial cost for one metre of sea level rise.[1] Santos et al. (AGU, 2021)Drivers of change of Thwaites Glacier, West Antarctica, between 1995 and 2015[2] Pine Island glacier[3] AntarcticGlaciers.orgSea level riseOn Fri, Jan 23, 2026 at 1:29 PM John Nissen <johnnis...@gmail.com> wrote:Dear John,Thanks for your interest. Trump's withdrawal from his invasion threat is good news. But the fact remains that the US, Russia and China are vying with one another for exploitation of the Arctic, attracted by reduced ice cover. This short-term thinking seems to be in complete disregard for the long-term catastrophic consequences of Arctic meltdown, one of which inevitably being metres of sea level rise without prompt SAI intervention.(The consequences of allowing the meltdown to continue are not just for sea level but for climate change: a further escalation in extreme weather events. Storm surges and river flooding will add to the problem of sea level rise for coastal communities. The situation is liable to get out of control without deployment of SAI within the next few years according to my trend analysis and engineering calculations - but I do not yet have a published paper on this. The good news is that prompt and appropriate deployment of SAI could actually reverse climate change and return the planet to a much safer state.)You raise three issues, the third of which certainly justifies a change of text, but I don't think the others do - I leave that to your judgement.1. Greenland meltwater causing at least as much meltwater being discharged from AntarcticaI specifically mention one mechanical mechanism, which is due to the way that West Antarctic glaciers are buttressed: they are typically retrograde, and buttressed at a grounding line. Thus raising the sea level accelerates the descent of these glaciers. Some are also buttressed by ice shelves which are separating from the terminations, partly due to the mechanical effect of sea level rise and partly due to warmer near surface water.I haven't managed to find specific papers to discuss these various effects, but I did google AI searches to confirm both the disproportionate sea level rise in Antarctica and the accelerating effect of raising sea level on Antarctic glaciers.(BTW, there is a second effect of Greenland meltwater on Antarctica which I could have mentioned but is rather complex. It is through the addition of cold freshwater to the surface of the North Atlantic part of the Atlantic Meridional Overturning Circulation (AMOC). This addition reduces the amount of brine produced when the surface water meets Arctic sea ice and melts it. The sinking brine is a main driver of the AMOC. The slowing of the AMOC has a heating effect on near surface water in the Antarctic which eats away at the glacier terminations, especially when the ice shelves have detached.)I can cite two examples of ominous precedence in the geological record. The Eemian had some thousands of years with a similar global temperature and sea level to our present ones. At the end of the period there was a collapse of Arctic and Antarctic ice sheets causing a sea level rise of 6-9 metres, with one third contribution from the Arctic and two thirds from the Antarctic, according to the climate guru, James Hansen. A second precedent was at the beginning of the Holocene, 11.7 thousand years ago, when the temperature measured from Greenland ice cores rose by 7-10 °C in around 50 years. The sea level rose 20 metres in 400 years, i.e. a metre every 20 years on average.2. Financial costThe estimate of $700bn per year came to me from John Moore who has carefully considered a paper by Brown et al; see [1]. If you look at Figure 4 and examine the cases where sea level reaches one metre or more, it is possible to establish an average cost value, summing the values for each different colour curve. John notes that the paper assumes sensible adaptation measures (such as sea dikes) are taken. He points out that many countries are averse to taking precautions as insurance against disasters, and those countries might suffer hundreds of times worse financial cost with a sudden sea level rise.The paper does not account for the cost of sea level rise in the matter of lives and livelihoods. The stresses from mass migration (or attempted mass migration) would likely lead to conflict. Overall there would be widespread economic collapse and a global security crisis, probably well in advance of the sea level reaching one metre.3. Arctic amplificationFour times was an approximation. A more precise estimate was given as 3.8 times in a paper here [2]. I suggest a change from "four" to "near four" for the letter.Kind regards, JohnP.S. I have asked Peter Wadhams whether he is happy to have his name included in the letter. This needs to be checked, if you decide to go ahead with publication.[1] Brown et al. (2021)Global costs of protecting against sea level rise at 1.5 to 4.0 °C[2] Rantanen et al. (Nature, 2022)The Arctic warmed four times faster than the globe since 1979On Thu, Jan 22, 2026 at 9:58 AM Letters Editor <letters...@ft.com> wrote:Dear Mr Nissen,Thanks for your interesting letter.I have highlighted some figures/stats in sections in bold. If you provide the sources for those.many thanksJohnDear editor,
A prime reason for Trump’s interest in Greenland is to exploit its resources, as recognised by a Danish investment fund’s ‘huge appetite’ to invest in Greenland (FT, 18th Jan)”. However, treating Greenland as a resource prize while its ice sheet melts is reckless. Greenland’s ice sheet holds enough ice to raise the global sea level by over 7 metres; a partial collapse could release over half a metre this century. [correct]
The dynamics of the planet means that this meltwater would directly raise sea levels in Antarctica, causing glacier collapse and raising the sea level by well over a metre. Once started, further collapse would be impossible to stop.
The financial implications are staggering: a single metre of sea level rise could cost the world $700bn per year according to one study. Even half a metre would devastate low-lying countries like Bangladesh and Vietnam, while several metres would obliterate coastal cities and agricultural areas globally. This is not a distant environmental concern, but a material threat to everyone on the planet: a threat currently ignored by nations competing for resources, sea routes and military advantage in the Arctic.
In 2012, I, alongside sea ice expert Peter Wadhams, testified to the UK Environmental Audit Committee regarding the urgency of protecting the Arctic. We warned that geoengineering was essential for Arctic preservation. Since then, Arctic temperatures have risen four times [think it's 3 to 4 times faster]faster than the global average, intensifying the risks from critical “tipping elements”, including the Greenland Ice Sheet.
A pressing need exists to start lowering the Arctic temperature while it is still just possible using the most powerful, available cooling technique: stratospheric aerosol injection (SAI). This technique mimics the cooling effect of large volcanic eruptions by injecting SO₂ into the stratosphere. Contrary to uninformed opposition, responsible research suggests that SAI could cool the Arctic with minimal risk of serious side effects, especially when compared to the risks from continued Arctic warming. The cost of such deployment has been estimated at around 11 billion USD per year.
While Trump remains determined to exploit Greenland rather than save it from meltdown, catastrophic sea level rise becomes inevitable.
Yours sincerely,
John Nissen
Chair of the Planetary Restoration Action Group, PRAG
8 Summerfield Road, Ealing, W5 1ND
On Tue, 20 Jan 2026 at 17:37, John Nissen <johnnis...@gmail.com> wrote:To: the editor of the Financial Times for publication
2026-01-20
The urgent necessity to halt Greenland meltdown
Dear editor,
A prime reason for Trump’s interest in Greenland is to exploit its resources, as recognised by a Danish investment fund’s ‘huge appetite’ to invest in Greenland (FT, 18th Jan)”. However, treating Greenland as a resource prize while its ice sheet melts is reckless. Greenland’s ice sheet holds enough ice to raise the global sea level by over 7 metres; a partial collapse could release over half a metre this century. The dynamics of the planet means that this meltwater would directly raise sea levels in Antarctica, causing glacier collapse and raising the sea level by well over a metre. Once started, further collapse would be impossible to stop.
The financial implications are staggering: a single metre of sea level rise could cost the world $700bn per year according to one study. Even half a metre would devastate low-lying countries like Bangladesh and Vietnam, while several metres would obliterate coastal cities and agricultural areas globally. This is not a distant environmental concern, but a material threat to everyone on the planet: a threat currently ignored by nations competing for resources, sea routes and military advantage in the Arctic.
In 2012, I, alongside sea ice expert Peter Wadhams, testified to the UK Environmental Audit Committee regarding the urgency of protecting the Arctic. We warned that geoengineering was essential for Arctic preservation. Since then, Arctic temperatures have risen four times faster than the global average, intensifying the risks from critical “tipping elements”, including the Greenland Ice Sheet.
A pressing need exists to start lowering the Arctic temperature while it is still just possible using the most powerful, available cooling technique: stratospheric aerosol injection (SAI). This technique mimics the cooling effect of large volcanic eruptions by injecting SO₂ into the stratosphere. Contrary to uninformed opposition, responsible research suggests that SAI could cool the Arctic with minimal risk of serious side effects, especially when compared to the risks from continued Arctic warming. The cost of such deployment has been estimated at around 11 billion USD per year.
While Trump remains determined to exploit Greenland rather than save it from meltdown, catastrophic sea level rise becomes inevitable.
Yours sincerely,
John Nissen
Chair of the Planetary Restoration Action Group, PRAG
8 Summerfield Road, Ealing, W5 1ND
Email: johnnis...@gmail.com
Phone: 07890 657 498
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