what does the warmest year on record tells global warming deniers?

i understand skeptics. they don't hurry to judgements preferring instead the slow ebb & flow of evidence to mount. so, isn't this enough? the consensus of scientists:

The 10 warmest years in the instrumental record, with the exception of 1998, have now occurred since 2000. This trend continues a long-term warming of the planet, according to an analysis of surface temperature measurements by scientists at NASA's Goddard Institute of Space Studies (GISS) in New York.

this is not appealing to authority. there's an interesting connection here.

don't we have a "trend" here? & if so, doesn't it it show probable causation?

the skeptic would say, what if it happened before? well, one can entertain the possibility of a non-human caused warming period in our prehistory. for instance the warming period in the mesozoic era. so what? why would that event be a counter to this one?

plus this:

Since 1880, Earth's average surface temperature has warmed by about 1.4 degrees Fahrenheit (0.8 degrees Celsius), a trend that is largely driven by the increase in carbon dioxide and other human emissions into the planet's atmosphere. The majority of that warming has occurred in the past three decades.

if you don't take this information into account you already passed the skeptic, you're a denier.