Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Can we use linear response theory to assess geoengineering strategies?   Geoengineering can control only some climatic variables but not others,
resulting in side-effects. We investigate in an intermediate-complexity climate
model the applicability of linear response theory (LRT) to the assessment of a
geoengineering method. This application of LRT is twofold. First, our objective
(O1) is to assess only the best possible geoengineering scenario by looking for
a suitable modulation of solar forcing that can cancel out or otherwise
modulate a climate change signal resulting from a rise in CO2 alone. Here we
consider only the cancellation of the expected global mean surface air
temperature. It is a straightforward inverse problem for this solar forcing,
and, considering an infinite time period, we use LRT to provide the solution in
the frequency domain in closed form. We provide procedures suitable for
numerical implementation that apply to finite time periods too. Second, to be
able to use LRT to quantify side-effects, the response with respect to
uncontrolled observables, such as regional must be approximately linear. Our
objective (O2) here is to assess the linearity of the response. We find that
under geoengineering in the sense of (O1) the asymptotic response of the
globally averaged temperature is actually not zero. This is due to an
inaccurate determination of the linear susceptibilities. The error is due to a
significant quadratic nonlinearity of the response. This nonlinear contribution
can be easily removed, which results in much better estimates of the linear
susceptibility, and, in turn, in a fivefold reduction in the global average
surface temperature under geoengineering. This correction dramatically improves
also the agreement of the spatial patterns of the predicted and of the true
response. However, such an agreement is not perfect and is worse in the case of
the precipitation patterns, as a result of greater degree of nonlinearity.

8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
26
The categories of this paper are: bayes-an
30
The categories of this paper are: q-alg
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
22
The categories of this paper are: chao-dyn