Evidence from the studies may indicate that CH4 emissions from combustion slip could be substantial, varying between 17.2% to 47.1% of total city-level CH4 emissions depending on the city. Slip emissions likely have a seasonal trend, which increase as temperatures decrease and more natural gas is used for heating . While this assumes that leaks from pipelines and other natural gas infrastructure do not vary seasonally, as operating pressures are held constant , we note that this may only be true for leak rates. In contrast to leak rates, operating pressure likely does not affect the number of leaks, which may be affected by seasonality and temperature changes. Metal shrinks in cold temperatures and thus may result in the emergence of new leaks from pipelines and other components involved in the distribution of natural gas during winter. These may be transient and self-resolve upon temperatures warming. More leaks from natural gas distribution infrastructure during colder periods of the year could challenge our findings, as these emissions would also correlate with metered gas consumption (which increases in winter), reducing the amount of emissions attributable to slip. However, it is unclear from the studies if seasonal changes in leak frequency in the natural gas distribution segment are noteworthy enough to substantially increase non-slip emissions during winter. Moreover, this phenomenon would be highly dependent on a city's latitude and annual temperature range and may not be a widespread issue geographically. If fossil fuel emissions do have a larger component of slip (instead of leaks), this misattribution could explain why annual emissions for Boston remain unchanged over eight years despite Massachusetts requiring that utilities improve detection, reporting, and repair of distribution pipeline leaks . Policies and actions to mitigate slip emissions may include servicing, repair, and efficiency improvements to appliances and other gas-fired equipment or replacements with electrified or other alternatives.