Astronomy in a Low-Carbon Future

The consequences of climate change are developing into a vast and unparalleled crisis, which is planetary in scale and yet very human in its causes and impacts. Faced with this truth, inaction and delay are neither ethical nor wise: every field of human activity, astronomy included, must take urgent steps to mitigate the crisis and avoid the worst potential outcomes, while adapting to those that are inevitable. We outline a strategy for climate-responsible scholarship and communication that we hope will resonate with the astronomical community's aspirations for a stable future in which there is room for curiosity and discovery. In light of the crisis, greenhouse gas emissions must be understood as significant research costs to be justified, budgeted, and rationed. Air travel is a major contributor. We must remove incentives in tenure and promotions for profligate travel, codify low-carbon practices, and reward efforts to minimize emissions while maximizing research. Any essential travel emissions must be fully offset, with carbon offsets that are reimbursable if not covered by the institution. The frequency, timing, and locations of conferences and colloquia should be planned to minimize air travel, with remote participation encouraged using online platforms. Conferences should favour lowest-impact food options by default, taking steps to minimize food waste (and other waste as well). Infrastructure must be planned with climate impacts in mind for both construction and operation. For buildings, this means pushing for designs and materials at the forefront of sustainable technology. For observatories and computing facilities, it includes justifying and thoroughly vetting the emissions footprint at the proposal stage and fully considering low-impact options, such as cloud computing. In education and outreach, we must strive to be reliable sources of scientific information on climate change, prepared to connect this to astrophysics and ready to direct curious people to authoritative sources. We recommended that CASCA support this transformation by establishing a sustainability committee (or office) to be tasked with conducting a community-wide survey of our greenhouse gas emissions and developing a decarbonization road map for the discipline. This committee would host sustainability forums and provide resources to support each of our other recommendations, especially climate-related materials and references for education and outreach. We recommend that CASCA push for climate-responsible governance. Governments, granting agencies, and universities must implement climate-responsible policies, like rationing the carbon budget of the entire discipline, using climate impacts to evaluate proposals, permitting the use of funds for offsets, and allowing climate-friendly but more costly travel options. Moreover, these entities must ultimately ration emissions to ensure that targets are met. To have an impact beyond the bounds of professional astronomy, we encourage astronomers to press their institutions to divest from fossil fuel extraction and its financing. Finally, we recommend that climate responsibility be an explicit priority in the 2020 Long Range Plan, and that it be used to guide all aspects of our profession, from our research and education practices to our infrastructure.White paper identifier W02