  The global climate crisis poses new risks to humanity, and with them, new
challenges to the practices of professional astronomy. Avoiding the more
catastrophic consequences of global warming by more than 1.5 degrees requires
an immediate reduction of greenhouse gas emissions. According to the 2018
United Nations Intergovernmental Panel report, this will necessitate a 45%
reduction of emissions by 2030 and net-zero emissions by 2050. Efforts are
required at all levels, from the individual to the governmental, and every
discipline must find ways to achieve these goals. This will be especially
difficult for astronomy with its significant reliance on conference and
research travel, among other impacts. However, our long-range planning
exercises provide the means to coordinate our response on a variety of levels.
We have the opportunity to lead by example, rising to the challenge rather than
reacting to external constraints.
  We explore how astronomy can meet the challenge of a changing climate in
clear and responsible ways, such as how we set expectations (for ourselves, our
institutions, and our granting agencies) around scientific travel, the
organization of conferences, and the design of our infrastructure. We also
emphasize our role as reliable communicators of scientific information on a
problem that is both human and planetary in scale.
