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| Climate change poses risks that demand to be treated as seriously as the threat of nuclear war, says a report commissioned by the UK government. |
Scientists from the UK, U.S., India and China say in a
report commissioned by the UK that deciding what to do about climate change
depends on the value we put on human life, both now and in years to come.
One of the lead authors of the report is Sir David
King, formerly the UK government’s chief scientist, who last month co-authored
a report on the scale of investment that should be made to move from fossil
fuels to renewable energy by 2025.
In a foreword to the latest report, Baroness Anelay, a
minister at the British foreign office, writes that assessing the risks
surrounding nuclear disarmament and non-proliferation means understanding
inter-dependent elements—including what science says is possible, what other
countries may intend, and systemic factors such as regional power dynamics.
“The risk of climate change demands a similarly
holistic assessment,” she says.
Value Human Life
She concludes: “How much do we care
about the effects of climate change? How important is it that we act to avoid
them? What probability of their occurrence can we tolerate? … The answers to
these questions depend in part on how we value human life—both now, and in the
future.”
The report is not the first to put
climate chaos and nuclear devastation in the same category of risk, but its
sponsorship by one of the world’s nuclear powers is eloquent.
It says the most important
political decision is how much effort to exert on countering climate change,
taking into account what we are doing to the climate, how it may respond, what
that could do to us, and what we might then do to each other.
The authors’ best guess, based on
current policies and trends, is that greenhouse gas emissions will keep going
up for another few decades, and then either level off or slowly decline.
This, they say, is for two reasons:
governments are not making maximum use of the technologies already available;
and technology is not yet progressing fast enough to give governments the
policy options they will need. In the worst case, emissions could keep on
rising throughout the century.
They warn that how the climate may
change, and what that could do to us, are both highly uncertain. “The important
thing to understand is that uncertainty is not our friend,” the report says.
“There is much more scope to be unlucky than there is to be lucky.”
High Emissions Pathway
The report foresees wide ranges of
possible global temperature and sea level increase. On a high emissions
pathway, it says, where the most likely temperature rise is estimated at 5°C by
2100, anything from 3°C to 7°C may be possible.
On this pathway, the chances
of staying below 3°C will become “vanishingly small,” but the chances of
exceeding 7°C will increase and could become more likely than not within the
next century.
The authors see very little
chance that global sea level rise will slow down, and every chance that it will
accelerate. The only question is by how much.
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| Extreme water stress and competition for productive land could lead to conflict. |
“While an increase of
somewhere between 40cm and 1m looks likely this century, the delayed response
of huge ice-sheets to warming means we may already be committed to more than
10m over the longer term. We just do not know whether that will take centuries
or millennia.”
A temperature increase of 4°C
or more could pose very large risks to global food security, and to people.
Humans have limited tolerance
for combinations of high temperature and humidity. Their upper limits of
tolerance are rarely if ever exceeded by climatic conditions alone, but with
temperature increase somewhere between 5°C and 7°C, it starts to become likely
that hot places will experience conditions that are fatal even for people lying
down in the shade.
Population growth alone is
also likely to double the number of people living below a threshold of extreme
water shortage by mid-century.
Sea Level Thresholds
Coastal cities, according to
the report, probably have thresholds in terms of the rate and extent of sea
level rise that they can deal with, but we have very little idea where those
thresholds are.
In a highly topical passage,
they say migration from some regions may become more a necessity than a choice,
and could happen on a historically unprecedented scale.
“The capacity of the
international community for humanitarian assistance, already at full stretch,
could easily be overwhelmed,” the report warns.
The risks of state failure
could rise significantly, affecting many countries simultaneously, and even
threatening those currently considered developed and stable.
But the report is not
relentlessly downbeat. “An honest assessment of risk is no reason for
fatalism,” it says. “Just as small changes in climate can have very large
effects, the same can be true for changes in government policy, technological
capability, and financial regulation … the goal of preserving a safe climate
for the future need not be beyond our reach.”
Le
solaire flottant: http://www.ciel-et-terre.net/hydrelio-floating-solar-system/
