14 September 2019 | New Scientist | 39H
UMANITY can only thrive if our planet
is hospitable to us, but what are the
limits to its stability? That was the
question posed by Johan Rockström in 2009
in the first scientific assessment of the limits
to safe living for humans on Earth. He and
28 co-authors called them the planetary
boundaries. They warned that if we exceed any
of those nine boundaries, we risk destabilising
Earth’s life-support systems and plunging the
planet into chaos. The good news, they said,
is that staying inside them provided a “safe
operating space” for humanity. The bad news
is that we have already exceeded four of them.
The boundaries have drawn plenty of
criticism, so does Rockström still stand by
the findings? Is he more or less pessimistic
about where we are headed? And where do
Harley-Davidsons fit in?Fred Pearce: What is the bottom line for Earth
and human civilisation?
Johan Rockström: For the past 10,000 years,
our planet has been in a uniquely stable state,
a warm interglacial era with largely unchanging
climate and ecosystems that we call the
Holocene. It is the era during which human
civilisation has developed, from hunter-
gatherers to digital technology. It is all we know.
But humanity is now driving changes like
global warming and species extinctions. These
threaten to push us beyond the thresholds“ The changes could be abrupt
and irreversible. We don’t know
where things may end up”
Ten years ago, Johan Rockström identified nine limits
for Earth’s life-support systems. We have already
exceeded four of them, but he is still cautiously
optimistic for our future, he tells Fred Pearce
>JSC/NASAFeatures Interview
Humanity’s life-
support system,
as seen from space