German Biologist: Global Warming Is Good For US
Wednesday May 09, 2007
Biologist Josef Reichholf discusses the benefits of a warmer climate for
animals and plants,large cities as centers of biological diversity and the
myth of the return of malaria.
Josef Reichholf is unconvinced by those who argue that global warming
will threaten animals and plants with extinction, and cause malaria to
spread in Europe.
SPIEGEL: Mr. Reichholf, are you worried about global warming?
Josef Reichholf: No. Personally, I'm even looking forward to a milder
climate. But it will also not pose any major problems for mankind
as a whole.
SPIEGEL: Where does your optimism come from?
Reichholf: The vast majority of people today already live under warmer
and, in many cases,
far more extreme conditions than we pampered Central Europeans.
Homo sapiens is the only biological species that can handle practically
any type of climate on earth --from the
deserts to the polar regions, from the constantly humid tropics to the high
of the Andes. Not even the animals that follow human society most closely,
have developed such an astonishing ability to adapt in the course of evolution.
SPIEGEL: In what sort of climate does man feel most comfortable?
Reichholf: Biologically speaking, we are children of the tropics. Wherever man
lives, he artificially creates tropical living conditions. We do this with warm
clothing, and with heated offices and homes. A tropical temperature of about
27 degrees Celsius (80 degrees Fahrenheit) constantly prevails underneath
SPIEGEL: But, as an ecologist, aren't you at least concerned about animals
Reichholf: Many species are certainly threatened, but not by climate change.
The true danger
comes from the destruction of habitats, such as the rampant deforestation of
tropical forests. Particularly as a conservationist, I believe that focusing on
effect is very dangerous. The climate is increasingly being turned into a
scapegoat, to deflect attention from other environmental crimes. A
typical example is the misleading debate over catastrophic flooding, which
is in fact caused by too much development along rivers and not by more
extreme weather events, which we can't change anyway.
SPIEGEL: What do you see as the greatest threat to plants and animals?
Reichholf: Industrial agriculture is the number one killer of species in
Germany. With their monocultures and over-fertilized fields, farmers have
radically impaired the living conditions for many animals and plants.
Many species have already fled from the countryside to the cities, which
have been transformed into havens of biodiversity. We are also seeing another
interesting phenomenon: Major cities, like Hamburg, Berlin and Munich, have
formed heat islands where the climate has been two or three degrees warmer
than in the
surrounding countryside for decades. If higher temperatures are truly so bad,
why do more and more animals and plants feel so comfortable in our cities?
SPIEGEL: And what is your view of the prognoses that global warming will
cause up to 30percent of all animal species to become extinct?
Reichholf: It's nothing but fear-mongering, for which there is no concrete
Evidence. On the contrary, there is much to be said for the argument that
warming temperatures promote biodiversity. There is a clear relationship
between biodiversity and temperature. The number
of species increases exponentially from the regions near the poles across
latitudes and to the equator. To put it succinctly, the warmer a region is, the
more diverse are its species.
SPIEGEL: Are you saying that the greenhouse effect could even help improve
biodiversity in the long term?
Reichholf: Exactly. And this can also be clearly inferred from the insights of
evolutionary biology. Biodiversity reached its peak at the end of the tertiary
age, a few million years ago, when it was much warmer than it is today.
The development went in a completely different direction when the ice
ages came and temperatures dropped, causing a massive
extinction of species, especially in the north. This also explains why Europe
such a high capacity to absorb species from warmer regions. It just so happens
that we have many unoccupied ecological niches in our less biodiverse
part of the world.
SPIEGEL: In other words, for you global warming means more flourishing
landscapes on the planet?
Reichholf: Indeed. When it becomes warmer, many species receive new habitats.
picture is clearly positive, as long as we don't destroy the newly developing
habitats right away by intervening in nature in other ways. It's no accident
that most of the species on Germany's red list of endangered species are the
heat-loving species. Many of them could e given new opportunities to survive
SPIEGEL: But aren't you underestimating the rapid pace of the current
warming? Many animals and plants are unable to adapt quickly enough to a
Reichholf: This claim is already contradicted by the fact that there have been much
faster climate fluctuations in the past, which did not automatically lead to a global
extinction of species. As a biologist, I can tell you that only the fewest animals and
plants are accustomed to rigid climate conditions. Take our little wren, for
example. Many would call it a sensitive little songbird. But the wren thrives just
as well in Stockholm as it does in Munich or Rome. It even lives above the tree
line in the Alps. The only places we don't see wrens are where there are no bushes
or trees growing at all.
SPIEGEL: But there are certainly animals that live in very limited niches. For
example,how would polar bears survive global warming?
Reichholf: Then let me ask you in return: How did the polar bear survive the last
warm period? Perhaps Knut at the Berlin Zoo is an exception, but polar bears
in the wild don't exactly survive by sucking on ice. Seals are the polar bear's
most important source of food, and the Canadians slaughter tens of thousands
of them every spring. That's why life is becoming more and more difficult for
polar bears, and not because it's getting warmer. Look at the polar bear's close
relative, the brown bear. It is found across a broad geographic region,
ranging from Europe across the Near East and North Asia, to Canada and
the United States. Whether bears survive will depend on human beings, not
SPIEGEL: Is there really no plant or animal species that isn't at risk of
extinction because of a further rise in temperatures?
Reichholf: I certainly can't think of any. There are a few flatworms that can
exist in icy cold springs. These creatures do in fact appear to be
in places where the springs are warming up. But this could also be a coincidence,
because the closest relatives of these worms tolerate a much broader
SPIEGEL: Conversely, should we be worried that malaria, as a result of global
warming, will break out in our latitudes once again?
Reichholf: That's another one of those myths. Many people truly believe that
malaria will spread as temperatures rise. But malaria isn't even a true tropical
disease. In the 19th century, thousands of people in Europe, including Germany,
the Netherlands and even Scandinavia,died of malaria, even though they
had never gone abroad. That's because this disease was still prevalent in
northern and central Europe in previous centuries. We only managed to eliminate
it virtually impossible that malaria would return to us purely because of
climate change. If it does appear, it'll be because it has been brought in somewhere.
SPIEGEL: Why has it become a dogma that we should be afraid of warmer times?
Reichholf: It's a mystery to me. As recently as the 1960s, people were more
concerned about a new ice age -- and that would indeed pose a great danger
to us. The most catastrophic eras were those in which the weather became
worse, not phases of warmer climates. Precisely because we have to feed
a growing population on this planet, we should in fact embrace a
warmer climate. In warmer regions it takes far less effort to ensure survival.
The interview was conducted by Olaf Stampf and Ger